The problem is there is little evidence (unless twisted) to show speed camera's work. If anything they can cause a problem with drivers braking sharply.
Not far from where I am sitting now a motorcyclist was killed trying to brake on a speed camera.
It is inappropriate speed that kills anyway, not just speed.
Speed camera's were just a money making exercise. If they really worked why close all of them, keep a few going and no one will know which.
Far better to put a plod in a jam sandwich.