You make it sound like it's a choice. I would assume that people don't choose to feel rage. I'd never get out of my car and confront someone but I absolutely yell at people when they either don't go fast enough, don't use their turn signals, ran a red light or any other type of thing.
it's a choice. people that act like that driving, usually don't act like that in a grocery store. they choose to act like that while behind a wheel though..
it's natural to be p'od when someone cuts you off. you may call them an A hole and a few other names. they can't hear you, not a big deal. when you become so mad, you go out of your way to terrorize someone for miles (or try to cause physical damage) then you chose to be a major a hole.