My biggest beef are those people who come to a stop at a green light and let others in cross traffic in front of them (and the 1,000 cars behind them).
How about idiots who enter intersections with nowhere to go? Thus making it impossible for vehicles on the cross street to go anywhere when they get the green. I spent a half hour trying to get through one intersection in Vancouver, BC, because of idiots like that. Maybe that is where you need a no right turn on red rule, because otherwise people feel that all the spots on the other side of the intersection will get taken by people turning right from the cross street.