There never gonna put camera's on you road if you can see them.
They've used their quota putting them on roads where there is no chance of stopping an accident, only causing them. Or roads they are guarentee'd to catch speeders on.
Think of it like this;
If the government wanted to, they could impose that ALL cars had speed limiters or trackers so that a car could not exceed 70mph or if gps tracked could be shut down.
They don't, because they only want the money. Simple.
How many skid marks or tyre marks do you see approaching Traffic light camera's for example. They are actually causing More accidents than they prevent.