Ps and Qs

A few months ago I wrote about the actions and responses associated with the apparently simple act of letting a waiting driver cut ahead of you into traffic (Alphonse and Gaston, 1/23/11).  After writing that I was curious to see if my perceptions about the ingratitude of those let in were correct or products of selective perception.  Historically, letting someone cut in front of you merits a wave, head nod, or smile.  So for the last few months I've been keeping track, informally, of the number of people who acknowledge the kindness of being let into traffic.   I've probably observed well over a hundred cars let into traffic, by me and others, and it appears that only about 30% of the people let in actually give the figurative thank you.  In fact, I've tried to note in general the behavior of people in "please and thank you" situations and am disappointed at how infrequently these words are used.  But I guess that is something that an "old person" would say, isn't it?