I think people have a certain comfort zone in their cars. You yell at people all the time in your car for cutting you off or not signaling or just being annoying. If you think about it, how many people do you see at Disneyland yelling and swearing at someone because they're walking in front of them in an annoying way? How many people do you see, flipping the person who just bumped into them off and then walking away. Why do we do it in our cars?