from:
http://www.transport.govt.nz/assets/Uploads/Research/Documents/Motor-Vehicle-Crashes-2012/Motor-Vehicle-Crashes-2012-Section-1-Historical.pdf
As you can see from the historic account of accidents, ( subtle differences over the years in accidents vs death and how they are measured by car by crash or per km travelled) the rates peaked in 1973 but rose till about 1987 and have fallen ever since, in the main you can put this down to better engineering of cars, airbags and ABS brakes .Jap imports helped as did roading design such as median barriers and dare I say it congestion. Speed is a factor but not as much as people think. 

Having sat next to about 2,000 people just before they each had a small, managed, low speed car accident. I can tell you that the vast majority of people, even when expecting a crash have no idea at all about vehicle dynamics, that's the basics of weight transfer around the suspension, the weight on the tyre footprints during braking, turning and accelerating, how long it takes to stop a car, what "their" car weighs, the size of the tyres. and most importantly a "feeling" for the weights and forces in the car. What's even worse is there is no requirement for a driver to know if their vehicle is front, rear or four wheel drive, has ABS, traction or stability control and to be honest, the plethora of three letter anagrams that no one has ever tried to standardise or simplify, make it even more confusing for a motorist to understand what functionality to expect from such systems in different brands of cars. We wonder why tourists crash rental cars !

So how can people know what to expect, when it all goes wrong, well, they can't. Hence, there are a very small handful of "Advanced driving schools" usually run by retired Motorsport competitors, that attempt to fill the gap, teaching the basics of car control and the preventative skills of using long distance vision and vehicle placement. Less than 1% of the driving population have attended such a session.

When licences are achieved in many european countries this type of education is mandatory.(Iceland Denmark Sweden Norway) despite similar speed limits and greater road condition variability their accident rates are HALF of ours. http://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate
Road safety experts, usually statistically versed, typically, have little regard for such training, sighting up-skilling as a danger rather than a benefit preferring instead to spend millions on road safety television ads. Monash University in Melbourne, where the vast majority of New Zealands road safety thinking is borrowed from, has made repeated attempts to furnish statistics to prove that up-skilling causes over confidence which causes people to take greater risks. A rather broad but statistically possible generalisation but one that fails to apply in Europe. The whole situation is odd though because education , situational familiarity and preparedness seems to be a pretty important factors in every other facet of life, especially dangerous ones,  except somehow for driving.    

As a system, we gave everyday nice people a licence to hurtle a 1,500 kg piece of steel around in almost any direction they choose, at up to 30 meters per second, without requiring them to have any education or psychological training, other than, the road rules and some very basic movement skills like turning and parking. In addition we also have humans doing the same thing but from the opposite direction with potential impact speeds of 200km/h with a small strip of delineating paint separating them (Just imagine OSH giving the green tick with those same figures, human controlled, in a factory. It would never happen.)

Yet at the same time as failing to provide them with a relevant education, we told them certain brands were "safe" and that "road" and "safety" could belong together without being quintessential oxymorons.  Next time someone tells you to drive carefully,  ask them "How?" The reply will be something along the lines of "keep within the speed limit, wear your seatbelt , don't drink and drive." People assume, because of the messages we've been sending them, that they are safe as long as they are travelling within the speed limit. Even car crash testing is made to look "safe" the vast majority of the car crash tests you see on TV are conducted at a maximum of 64km/h, that's all that the major crash testing standards require. No Car maker in their right mind would show you their cars being crash tested at 100km/h.

Now, with the assistance of the internet, a dose of reality. Here is a two car head on collision - each car traveling at 100km/h (62mph)  both cars were driven by remote control Volvo and a BMW, a bit old now but statistically safe and sturdy cars http://www.youtube.com/watch?feature=player_detailpage&v=Y5vbNbxD6bw#t=165s

Here's a slightly more modern car, still remotely driven, into a crash wall at 192km/h: http://www.youtube.com/watch?v=l4PjSVOnrVg&feature=player_detailpage#t=178s

Is 100km/h a safe speed to travel at ? If the speed limit was there purely for the purposes of ensuring safe impact speeds it would be about 25-30 km/h. So forget 100km/h as a safe speed, forget 70, forget 90, forget 101.

Whilst this crazy situation is not the fault of any one individual, although one would think intelligent humans should be more curious when it comes to understanding something so dangerous, that they engage in on a daily basis.

Monash and LTNZ also have a bit of an issue with motorsports people telling people how to drive, which is a pity because the motorsport competitor is constantly aware of and looking for all sorts of factors that have to be constantly kept in check to get them around the track, whilst motorsport competitors do this largely for fun, it's a tough job and for the drivers, they are constantly checking their own psychology on one hand keep the car smooth, balanced and pointing in the right direction.
They are also quite critical of their own driving. Ok it's not rocket science but if it's done properly it gets 100% concentration 100% of the time.

Motorsport competitors know that a large moving weight, is really dangerous, some of them have lost fellow competitors in the sport, they see accidents on a more regular basis than road users and they tend to be more mechanically minded so they have each done quite a bit of thinking about the physics of what they are doing. Most both visualise and feel the chassis and to determine how it will behave  Of course, they wear helmets, head/neck protection systems, 5 point harnesses with wider straps and before they start racing have quite a few years of club level experience. Still, despite all the safety gear, the lack of traffic, the huge tyres, the roll cage, the better suspension, their elevated skill level and practiced thinking, they concentrate hard. Really hard. 
These people however will be the first to tell you there is no magic safe speed for any road, its variable. It changes, all the time. The drivers job is to monitor the environment and make decisions through visual observation, feeling( the car), thinking and finally by control, quite a complex task and it would not be made any easier by diverting the drivers attention to an instrument on the dashboard every 5 seconds as prescribed and advised by current learn to drive practitioners and encouraged by the press releases we saw the other day.

Let me also just say at this point I don't think the use of excess speed is a good idea on a public road, at all. I don't think the speed limit should be higher. We all need to drive at roughly the same speed to ensure flow. That speed should give sensible margin for unexpected errors. But before we bath in the ideals we should consider how it's possible for a driving population that didn't get the right training, to judge the right speed to travel at.

One comment I heard a lot from motorsport people was that drivers on the road travel way too close together ( 2 secs is way too close)  too close to the centreline and too fast in the wet/dark or in poor visibility.  Speed is an easily measurable factor , hence it's easy and dare I say it, profitable, to legislate against certain levels of it. Concentration levels, vision length and following distances, which absolutely do dictate the outcome of a scenario, are not thought of as measurable. Pity - because most drivers are psychologically at risk of failing to concentrate.
You might ask why this is when the physics of driving suggest the activity is really dangerous. The drivers concentration isn't as intense as it should be because there are less regular reminders of the speeds and forces present and no natural signs of risk, Motorsport competitors seldom, "forget to look", or "doze off" or "lose concentration" because they are highly aware of the environment. They don't fiddle with the stereo or send texts or point out nice scenery because that would be, well, screaming dumb . Tightrope walkers also, seldom lose concentration, they have a natural reminder, all the time, height.
If there was a crocodile in your room, you would be fixated on it, not for a second would you be thinking about if you had left the oven on. In a modern car the danger is further obscured especially to those who are unaware or disinterested in driving.  
Power steering, modern suspension , radial tyres and years of vehicle design and noise insulation mean a modern car is now a quiet cocoon of luxury rather than a place to recognise and evaluate deadly risks. 

A quick look at our roads gives you another clue. Long straight roads are in essence boring, they don't require the driver to do much, so they don't, drivers become accustomed to having less to react to, they switch off for brief moments, they stare at the vehicle in front and become accustomed to just hanging on to the wheel an following the car infront. The long straight roads also have the highest prevalence of head on crashes ( Ruakaka -Whangarei, Sanson - Levin Desert Rd) Drivers clinging to the centreline, especially at night, especially at speed and especially when tired, they did not get to practice their familiarity with the location of the left hand wheels and drive to the left of their lane.
Fatigue wasn't as much of an issue when drivers had to manhandle older cars around twisty roads. Today the second anything goes wrong we blame the roads, we spend millions re-engineering perfectly traversable roads because drivers forgot to concentrate, they failed to identify and appreciate the risks, they failed to grasp just how dangerous driving is.

In my mind it's too late to do anything meaningful to properly educate the populous and autonomous cars are just around the corner anyway,  but these have been my reasons for thinking it's the wrong approach to blame accidents on minor speed infringements.  

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