It seems like an easy enough thing, but they just don't get it. You talk to new waiters, they worry about every single tip, what they made, they think they deserve 20% every time, and you try to explain it to them, this isn't what they should be worried about, they should be worried about giving good service, "treat people well" I tell them, the rest will sort itself out, you're not going to win them all...
Still they check every single tip, complain about the bad tippers, it's an easy trap, disregard all the great and superlative tippers because you had a few people stiff you, if there's a philosophy to serving or hospitality it's not about the tips, not at all, it's just about treating people well.