Back when I was learning to drive (early '90s, is Southern Ontario), I remember being taught to do things like flash beams at a passing trucker, so that they know when it's safe to pull in front of you, or to blink your running lights or turn signal briefly as a thank you, when someone lets you in on a crowded lane change. None of this was a "you must do this", just "it's polite to..."

Back then, this behaviour was extremely common from commercial truckers, and somewhat common among the general driving populace. Now, it seems that I don't see it at all. I don't remember the last time I've seen anyone do this, except myself.

So, was this something that was more of a regional thing to begin with? Was it common across the US/Canada (or other locales)? If so, is it still common in your area?