As a driver...
Know what? I'm usually a driver nice to pedestrians. I stop and let people (and animals) cross, especially if it really is at a designated pedestrian crossing. But if I let you cross, then you walk reallyREALLY*REALLY* slowly, keep chatting and laughing with your friends, keep using your mobile phone while crossing, and you cross at a diagonal path instead of straight across and thus keeping you in my way longer than can be avoided? Man, oh, man, I get this strong urge to do society a favor and make sure you don't get to pass your stupidity and inconsiderateness.