It is well believed that speed cameras are usually abused used as revenue generators and this report clearly shows a good example with the police focusing on speeding areas than frequent accident areas, since GPS' obviously don't collect accident information.
Another problem with speed cameras is the delay in getting the fine: If someone gets pulled over by the cops for speeding, they are immediately punished and chances are that they'll be watching their speed more carefully after that. However, if someone gets caught by a speed camera, it could be several days before that person gets the ticket and a higher chance of receiving multiple fines from the same or repositioned speed camera by the time the first fine comes through. Here in Ireland, it can be 2 or more months before the fine comes through in the mail.
In my opinion, rather than focus on speed cameras, the cops should be looking at improving the cameras to look at other types of penalties, such as a front-facing camera that detects if the seat belt is fastened, if the driver is using its mobile hand-held, etc. with suspect images being reviewed by an officer before fines are issued. Even without the technology, simply taking a picture of each passing car and reviewing a random sample of 1000/day would be effective at finding a handful of offenders and make an effective deterrent, much like a cop at the side of the road checking for such offenses. These are the only type of cameras that really should be called "safety cameras", unlike speed cameras that check speed only.