Here in the UK many so called safety cameras are nothing more than cash cows for a Government which is obsessed in taking money from us by stealth. As a truck driver I have seen hundreds of the bloody things which are placed in areas doing nothing for safety, but doing the maximum for fund collection, this is what pisses people off the most.
As for speed limits, most are now outdated as they were set in the days of cars with drum brakes which did take a week to stop from 60mph, the modern car is now much advanced in the braking department.
By the way I have no axe to grind, as an HGV driver for 30 years with a clean license, and never been done for speeding......