Alternatively: cameras take care of catching the speeders, freeing up the traffic police to concentrate on other offences, such as uninsured and dangerous drivers
If only that was the case – the reality seems to be that the cops spend just as much time workign on speeding, whilst there are also less of them.
Really? Because most areas require a given number of incidents or fatalities to occur before a camera can be placed.
Only if they want to keep the profits from the camera (rather than them going straight to central government). In any case, you should check out the actual rules – the incidents don't need to be at the camera location, just within a given distance, and they don't need to be speed related. The former allows them to put a camera on the bypass safely taking traffic away from the urban area next door where there have been incidents. For the latter IIRC for one camera location one of the required incidents was somebody getting injured falling over on a moving bus.
Of course the point can be immediately disproved by various brand new roads which have cameras on before they open.