flipflops

My am commute is about 6 miles and I'm out between 7:30 and 8am. I take pains to follow all the traffic laws-- I signal, I stop at lights, I try not to make any sudden moves that would freak an inexperienced driver out yet I constantly get honked at yelled at tailgated in bike/bus lanes (in alot of places in LA, during rush hour bikes can share lanes reserved for buses-- so these folks aren't even supposed to be in the lane).

Why are people so hostile to cyclists-- I'm just trying to get to class. Can anyone explain this to me? I'm a woman and I ride by myself most of the time so occasionally I get a little freaked out when people are aggressive. Can anyone explain the intense hostility people feel towards cyclists? Is it because we're slower than a car?-- It's not like they can't just pass me. Any thoughts?