The only purpose of law enforcement traffic cameras is to generate revenue. The people operating the cameras take roughly half of the revenue, with the other half being divided up between your local police and other local departments they might say they are supporting (like road crews fixing potholes and the like). But, generally these things are set up to "trap" people and to extort money from them.
Red light cameras, in particular, have been proven to adjust the timing of lights, giving people less time to get through a light and create more stressful traffic patterns. This does two things. One, it creates red-light violations that would not exist without the camera (since the camera slowed down the yellow light timing) and it causes accidents as people brake early to avoid the fine, get rear-ended by people behind them expecting to make the light, and potentially pushing them into traffic causing further damage. That's why a lot of cities have gotten rid of them. The money they were making wasn't worth it, and they were paying scummy people to make their streets less safe!
The more safe solution is to fix what is congesting traffic in the first place. Roundabouts in place of intersections are a nice, short-term solution. Better public transportation is better.