Years ago I read an article about them in the LA Times, the red-light cameras. They started out putting them at intersections that had either a lot of crashes due to people running red lights, tickets, or complaints. Now, the company that monitors these cameras charges a pretty substantial fee, and the fee went up as the city added more cameras.
But, at first, they were giving out a lot of tickets so it was a profitable venture. And they worked- fewer crashes, fewer people running red lights, which meant fewer tickets being given out. But the monitoring fee remained the same, so it was now a losing proposition.
So the city started shortening the length of the amber light...thus encouraging people to run red lights, thereby increasing the likelihood of crashes and smashed pedestrians. All to generate more revenue.