Not at all. Look at a political map of the area and you'll see that these folks fancy themselves as victims of an unjust world and they're angry. Just 20 miles from the center of Lake Washington (in any direction) you'll find that people wave.I'm not saying it's good or bad, but should I just stop waving since it appears to be a regional cultural thing? After so many years of MTB and motorcycling not waving feels like I'm being a dick.
It is a cultural thing but not indicative of the PNW.