It is all about money.
I have few qualms about govt security cameras in general if they are used to solve crimes - but the traffic cameras are about generating revenue. They tend to get placed at poorly designed interestions rather then places that have had accidents.
In DC they have one in the tunnel that routes 395N to New York Ave. - no intersections and no pedestrians - just open road - it is about making money.
You just want to run redlights, right?