I have to admit that it is probably something of a national character trait that we don't complain enough about bad service/food/anything else. There really is an underlying "Don't make a fuss" attitude which means that things have to be REALLY bad before we compain. Maybe the poor service standards in many places are at least partly caused by that.
Regarding Sir/Ma'am, I fell into using them while in the States and have continued to use them ever since (although perhaps not quite so frequently here). It just seems like a nice part of English usage which has been lost in Britain.
Mind you, Britain does retain the heavy usage of "Thank you" at times. You know the sort of situation in a restaurant:
Waitress places knives and forks on the tabe. "Thank you."
Waitress walks to other side of you and lays a napkin down. "Thank you."
Waitress returns five seconds later with salt and other assorted seasonings. "Thank you."
Even as a Brit I have to say that it seems a little excessive at times.
The consequence is that Americans are sometimes seen as less polite for not inserting "Thanks" after every single action. Maybe you could counter any such criticism with the Sir/Ma'am issue?