Happy to oblige.
I don't know where you're from, but in the U.S.A., overt harassment of cyclists is a fact of life. Here is a collection of testimony from Austin; here is a collection of testimony from all over. Then, of course, there’s that doctor from LA who was convicted of trying to kill cyclists on purpose. If I had a dime for every time I’ve been verbally or physically attacked while biking, I'd have...well, probably enough money for at least three tacos at my local taqueria. But that's quite a lot. I'd challenge you to find a daily bike commuter in the U.S. -- anywhere -- who has never experienced open anger and aggression.
And what is it that one's fellow-citizens yell from their cars? Almost always, "FAGGOT." Lots of evidence in the Bikeforums thread I linked above; lots of evidence from my own experience; and here’s a pretty amazing incidence of unbridled rage and homosexual panic among the police (who are supposed to represent social order and authority). If you grew up in the U.S. (or a lot of other places), you'll recognize this as the sign of a member of a majority who feels threatened by a minority that he does not understand, and thus feels compelled to denigrate. Women who bike for transport (including my wife, and this person ) report sexual harassment by strangers at much higher rates than women traveling by other means. Obviously, it’s only a small minority who actually harass strangers on the streets, but they wouldn’t do it if they didn’t perceive themselves to be in a position of social dominance. This kind of harassment only happens where a dominant group wishes to oppress and ostracize a subaltern group it hates and fears. (When a bunch of young men in a pickup truck yell “BREEDER!” at me, I’ll know this country has really changed.) I'll let Mikael testify as to whether this kind of thing happens in Copenhagen or not, but I'll be willing to bet that it’s rare – a cyclist there is just a person who happens to be riding a bike, not some threatening Other. That’s not the case here.
Beyond the overt aggression, you’ll find a million subtle slights that indicate fear and panic (the most common: the passive-aggressive “you be safe out there” that really, in its tone, conveys “you’re a _____ing crazy freak!”). Most importantly, there’s the brute fact that no one here uses a bike (or even walks), even when it’s easy to do. I live about a mile from the nearest supermarket. About ¾ of that mile is on a separated greenway, and the rest is pretty easy to negotiate. No hills, no snow. And yet I’ve never seen anyone from my neighborhood (other than myself and my wife) ride a bike to the supermarket. I also work on a college campus. One of my co-workers lives about a ten-minute walk, or three-minute bike ride, north of our office. Yet, every day she drives in her car all the way around to the south side of the campus, parks in a lot, and walks five minutes back north to the office. All in all, it’s slower than walking and much slower than biking. Yet, she would not consider “going to work” in any way other than by car – it simply does not fit into her worldview.
Yes, these are all anecdotal bits. I’d love to see a decent psychologist do a study of this stuff, but as far as I know it’s never been done. Dave Horton is doing some interesting work, though. And I’ll bet you a new bike that that when that study does happen, it supports my conjecture. Whaddaya say, sport?