you can't install properly configured red light cameras. As soon as you do people start either a) driving around them or b) stop running red lights. They seem to work too well, and then the revenue drops like a rock. Whatever else we want debate about how effective they are they're there to generate money for cash strapped cities not allowed to raise taxes; Safety may or may not be a byproduct, but one thing is sure: less light running at the intersections their put into is. And sooner or later to keep profits up they have to game the cameras to give out more tickets...
And you're right, fixing safety is really, really simple. Just run a yellow for a few extra seconds to make sure the intersection is clear. It costs nothing, but it also doesn't generate any revenue.