I think that in most cases, car drivers aren't out to get us for not being one of them, but are just reacting to us as they do to all other slower moving vehicles. I often get cut off, tailgaited, etc while driving my car (at the speed limit!). I think it's easier to take it more personally while on a bike because you're more exposed, and so it is more dangerous. Car drivers don't necessarily see this difference, especially if they don't cycle. They don't know we're avoiding obsticles they don't need to worry about. They don't know what it feels like to get buzzed. They just see us as another thing slowing them down. If I were in a car slowing down another car, I'd also get some kind of negative reaction, and it would probably be done with even more intent and aggression.