In San Francisco

I'm at my friend Steph's in San Francisco and have been up for almost 24-hours, though I did take some naps on the plane. My inclination when I visit new places is to make generalizations about the people who live there. When I walk into a coffee shop or store, I categorize everyone as a San Franciscan and view their actions as reflecting upon the vibe of their city. The crazy man who yelled at the clerk at Green Apple Books in Inner Richmond about how he "controls his own money" and "wants to be respected" (yeah, this guy was nuts--he was even carrying a rain stick!) is an emblem of the zany tendencies of some of the San Fran residents. The kind people who smiled at me when I moved my bags out of the way for them on the bus are imbued with a California calm that allows them to be much more considerate and thoughtful than the people out East. Today a car almost hit me making a right turn when I had the right of way, but rather than speeding through the turn or glaring at me, the driver actually waved apologetically. It's nice that people have some remorse for their unintended recklessness. Is this San Franciscan, though? Is speeding like a frazzled, over-caffeinated a-hole Distrcit of Columbian? Why is it so tempting to generalize about a locale, anyway?