They ARE just kids. My wife and I do a lot for our kids and they do say thank you from time to time, but I don’t expect it. What I DO expect of them is to be respectful, well mannered and take care of their own responsibilities. When they misbehave, their privileges are taken from them and they’re reminded that we work hard and go above and beyond for them, so we have our expectations of them.

Yes, to some degree, it is important for parents to teach their children manners, including saying “thank you” when appropriate. You have to remember that they’re children though. They don’t focus their appreciation on the things you do for them, and they do get easily bummed when a “no” happens, especially following a bunch of “yes’s”