If somebody needs the positive proof why speed cameras exist, they should look no further than this:

The drop in fines suggests that police chiefs decided to put fewer resources into speed enforcement when they stopped being able to recover the costs of installing and operating cameras.

In other words: The moment the police was denied the gains of their action for financing any other side activities, the constant fleecing of motorists stopped since it cost more than it brought revenues. And the drop is quite spectacular:

Thames Valley Police recorded the steepest fall in camera fines, down from 137,000 in 2006 to 54,000 in 2007.

In all of the UK, the drop was 23%, but that's just an indication that quite a few police districs haven't noticed they aren't going enjoy their gains anymore. If the cities down here stopped getting money from their speed cameras, I'm very confident fewer would exist. The same holds true for parking fines.

In Switzerland, the city of Zurich would be in a world full of hurt if this happened since they're the record holders when it comes to bolster the city finances by 'enforcing' traffic regulations while being on soft on violent crime or real traffic criminality like prosecuting all those who burn red lights by installing pure red light cameras (with the same system as the Austrains for indicating that the red is going to turn red - flashing the yellow light 4 times before it's red in order to avoid having many rear-end collisions).