In Japan people are friendly, the roads are busy enough that people don't take their eyes off the road. Tokyo is a kind of strange place in that everyone seems to exist in their own little bubble, and don't pay much attention to anyone or anything outside it. In the American Southwest, everyone waves, cars, pickups, motorcycles, or bicycles. In Tokyo out on the Tama, Arakawa, or other cycling courses, maybe one-in-ten other cyclists will wave. The one who waves is probably not from Tokyo.