Cycle infrastructure, even.

There's really no winning as a cyclist when most people are in cars. If you stop at all stop signs, and obey they right-of-way, people will yell at you and/or try to wave you through ahead of your turn dangerously. If you do an Idaho stop (which is the safest way to approach a stop, whether it's legal or not), people will honk and yell at you and possibly try to run you off the road.

I used to commute by bike a lot during rush hour. If there was a lineup of cars waiting at a red-light, and I just waited in line, people in cars behind me would honk at me as if me preventing them from being one cars-length further ahead in line would somehow affect them. If I filtered forward, like I should, people would actually edge their cars over to try and block me.

I think for the most part, it's misplaced anger from drivers who don't want to face the fact that they are the source of danger on roads. The worst bicycle collision is way less severe than a car crash. They also really hate when bicyclists can get anywhere faster than them, which is often the case because it shows them just how much time they waste being traffic.

Except Berliner cyclists. They scare me.