Do you know what the word tip means? It really is an abbreviation: To Insure Promptness.
On the other hand…
Some sleep away camps do not pay staff as they assume they will get tips. Unfortunately, not all staff are in “tip positions” (waitress/counselor) and are never compensated for their time at all. I know someone who worked several jobs at a camp, assuming she would “split the pot” of all tips received, as she was lead to believe. She worked the whole summer, paid to do so, and received no money whatsoever. I know the girl was upset at the camp for a while as she felt taken advantage of.
But based on the definition of the word- it is not mandatory but is there to encourage the workers to work faster/better.