That is called empathy or compassion. It takes so much more self control not to lash out.
Americans sue big companys all the time over anything and everything, that is fine. But lash out individual workers, be it waiter/waitree or store workers, is considered rude and barbaric. If those people don't do their job correctly, you suppose to tell them nicely, which stems from the belife "treat people the way you want to be treated". In an other word, it is about "lead by example" and not "get my money's worth".
