I don't just tap my horn in those cases, I blow the horn continuously until they move. One woman in the Bay Area got so mad at me when I did that she stopped at the intersection until the light turned yellow, and then blew through the intersection herself as it turned red, making a U-turn, ensuring that I would have to wait for another light cycle. As she passed by I gave her an additional gesture of my ill-will.
Wouldn't it be nice to have some sort of telekinesis power to cause four simultaneous blow-outs on a target vehicle?