When I was growing up, one of the first things kids were taught was to say please and thank you. I know that's still the case in many families. Which is why it surprises me that this simple courtesy of expressing thanks when someone does something for another, no matter how small a thing it is, is too often forgotten.
Now it's possible that I'm an old extremist when it comes to this matter. I say thank you when when the checker hands me the sales receipt, when a waiter refills my water glass, and if traveling through Oregon, I say thank you to the gas station attendant who can't by law allow me to do it myself.