I think yelling at motorists don´t have any pedagogical value, but violence against his vehicle and mind have. Here we have a working class who make deliveries by motorcycle of everything, like food and documents, as quickly as possible to make more money. We call them motoboys. Since the streets is filled in every space by cars, they use the gap between them to go. But they had a big problem, motorists here likes to swerve without any signal, suddenly. So, when motorist is changing lane and a motoboy is caught by surprise, and nothing occurs, he beats the side mirror to death. When he falls his comrades smells it, and a swarm of motoboys comes to terrorise the motorist. Now motorists are more attentious in gaps where motoboys might be.

Here a image to illustrate the scenario.
http://imguol.com/2013/01/28/28jan20..._1920x1080.jpg