Jase2985:
everyone has missed the point that all the speed measuring equipment has an accuracy related to it, so the police couldn't possibly enforce a zero tolerance due to said accuracy. they would be up for a few law suits if they started ticketing people at 1-3kp/h over the limit.
There are no lawsuits in NZ (mostly). People could defend the charges, but the cost of doing so would dwarf the small fine. The equipment is gazetted and certified for use so that argument won't fly (unless somethings gone wrong because the certificate has expired or similar), and there are practical reasons why the device will in most cases read lower than actual speed (i.e. Doppler effect).