Green means go, right?

I remember when I first started writing serious mathematics, being given some important advice by a professor:

"Use the same symbol to mean the same thing, and different symbols to mean different things."

Obvious, right? Well, it's not something that's been applied to the American traffic system. That is, green does not always mean go, and red does not always mean stop. For instance, in many states, you can "turn right on red", meaning you can make a right turn even if you have a red light, so long as the road is clear. At most four-way intersections with lights, if you have a green light, you can only turn right or left if the way is clear - and this includes pedestrians. So the pedestrians crossing the road have right of way, even if you have a green light. It is my opinion that this unclearness leads to much bad driving, as evidenced by the fact that I almost died this morning when a car tried to turn left into me.