As a cyclist in San Francisco, one has to be careful when riding to be sure that one doesn’t get hit by motorists who aren’t PAYING ATTENTION.
One way that motorists can help everyone stay safe is to use their turn signals. I don’t know how many times I’ve almost gotten hit because somebody in a car started to turn without using their signal. And when I scream in their windows “TURN SIGNAL!” Somehow I become the bad guy, and horn honking, cursing, and maybe a short chase usually ensues.
How people so clearly in the wrong can take it to that level is beyond me. But know one thing drivers: I’m not trying to make you feel bad, or to enrage you. I’m just trying to make it to my destination without dying. So share the road, and follow its rules. Some people would do more to your windows than shout in them.