Speed is not the issue per se. It's speeding when driving conditions are not suitable. Many European countries have speed limits of 130kmh, and even if they are lower, the average cruising speed is close to 130. In the US, most interstates are limited to 70/75mph (112/120kmh) and yet most people still drive 80mph (128kmh)
NZ has one of the lowest speed limits in the world however NZ also some problems to deal with: - windy roads with unsuitable speed limits (I would get rid of the blanket 100kmh open roads limit tomorrow and replace it by speed limits per section) - narrow roads with insufficient room to overtake (I suggest upgrading most of the densely trafficated stretches to the Scandinavian 2+1 road system) - a general "lazy" driving attitude.. not pointing the finger but lots of folks drive around in their automatics, 1 arm out of the window whilst sipping coffee or smoking a fag (equals no concentration on environment or other road users) - city drivers not adapted to rural conditions (when people cruise into the countryside for holidays or to visit friends/relatives)
On dual carriage ways that are built to 21st century standards (wide lanes, wide hard shoulder, new tarmac, latest safety features such as guard rails and lighting) it would be perfectly sensible to allow a 110kmh (or potentially even 120kmh) limit to relieve the psychological frustration of always having to drive slow. Cars have modernised and so have the roads so where restricting on one hand, give a favour back as well
What I am completely opposed against though, are nutters that speed in urban areas. Doing 80 or even 100 in a 50 is far more lethal than doing 120 on a 100 stretch. Hopefully these cameras will be focussed on such areas rather than generic "revenue generation" along straight stretches of road.