The fact is plain, if the public didn't speed there would be no speed cameras, simple as that. No one would bother spending money on cameras to catch the odd driver who drifts over the limit by a few mph before realising & easing off to the limit.
The cost of installing, maintaining & operating these cameras is high & it's only the fact that lots of drivers are caught (probably only a small percentage of those who do speed) that it is economical to keep them in operation that they are still around.
As I have said many time before they are not safety cameras (that's why if I refer to them as 'safety cameras' I normally enclose them in single quotes), they are speed cameras & are there purely to raise money.
Maybe at first they though it would keep drivers within limits but by now they should know they don't work. Speed is not the issue, it's bad driving which includes inappropriate speed (which could be too slow as well as too fast, based on traffic flow).
Yesterday I was on a DC with a 50 limit, I was doing 55 with the main flow (lane one) & we were getting passed by cars at speeds up to 100mph (my estimate), the majority arround 65-70 (lane 2). Some of the 65-70 drivers were being UNDERTAKEN by the faster one who then cutting them up to get back in to lane 2.
I am by no means anti-speed (I try not to speed because I can't afford the fine and/or losing my licence) & prior to speed cameras though nothing about speeds up to 120mph (in a car) on any road (only if safe to do so). Those day the police would just give you a 'ticking off' if they considered your driving to be safe based on conditions at the time.
Oh for the good old early 70's, those were the days.