One negative comment, a disagreement with or even the subtlest criticism toward a fellow human being will necessary ignite a fight, full of uncalled for insults. We are incapable of addressing or discussing issues when someone is judging our behavior or actions. Instead, we habitually get defensive and temperamental. So much for mature, civilized, western society.
The next time you cross the street and some driver doesn’t notice you, coming a bit too close to you, try not to do what anyone else in SF would do – try not to stare him down or yell and cuss at him. Chances are quite high he didn’t try to run you over on purpose, and he is already scared of what might have happened.