Years ago, at a city intersection, I made a right turn on a red, when all traffic was stopped, before the opposing traffic light turned green. Then the light turned green and a guy pulled up on my right at the next light,honking and yelling, and I made a "what's up?" "sorry I offended you" sort of shrug. He kept screaming and ranting. He was pulling and pushing on his cars steering wheel so hard he was bending it, I expected to see it come off in his hands. Then his antics became so over the top I started laughing. Then he really got going, actual foam was coming out of his mouth, along with the words "I am going to kill you, you want to get shot?! And other words.
I stopped laughing then and started planning. It is really odd how quickly one can think with the right stimulus.
Millcreek is right- I think there are a lot of people out there just sort of hanging on, with a huge internal problem, and any perceived slight, is enough to give them an excuse to erupt. They can't afford to let it out to their boss, or their wife, or anyone else they know, and it builds and builds , and any stranger becomes fair game, and in their car they feel anonymous enough to let go. After the rage takes over for a couple of seconds,, they are so pumped with adrenaline they will do anything.
I feel sorry for them, seriously- I have met a few mentally ill people and it is the worst of afflictions.