Doc, I would say 80% of people do not say thanks, but that has never deterred me as it is not why I choose to send a gift to anyone.
Yes it is courtesy but that seems to be a dying breed.
This game has changed for me and I am not convinced I like the way the company is heading. Out of the money I have put in over the last few months, probably half has gone in gifts. That will soon change.
Doc and to all the generous Santa's and Elves, Thank You! (on behalf of those incapable of saying those two words).