no, Rhyme, I don't agree. The anger and aggression comes from within the angry aggressive person. While he's cussing you out, he's not thinking of bike messengers in Chicago, he's thinking about the fact that you're slowing him down.

I don't think very many people are driving down the street thinking about the idiot on the bike they saw a month ago. They're thinking about the fact that they are late to a job they hate, their girlfriend just left them, some personal stuff, and there's a bike. I HATE BIKES!!! instant anger. that bike's in my way. how dare they get off the sidewalk!

And then there's that thing about being in a car that somehow dehumanizes people. They are protected by this glass and metal box from having to see your eyes, your skin, your human-ness and all they see is something that is impeding them.