Tips are Gifts. According to the US tax code you can give someone a Gift up to a certain amount and it is not taxed. The amount is over $10,000.
So I can give a Gift of $10,000 to anyone and they will not have to pay taxes on it unless they are someone who brought me a drink. Then the dollar I Gifted them is suddenly Income.
If I give someone a Gift of money then it should be a Gift regardless of what their job is.
You are actually arguing for exactly what you claim to oppose. Taxing only certain people.
If tips were simply a gift then waiters and waitresses would not receive a lower wage because part of their income is tips. Tips are normally not just a gift. “TIPS” stands for “To Insure Prompt Service”. They are actually part of the wage paid by the consumer directly that is based on the quality of service provided. If you want to give a Gift then you better find a way to do that is not in relation to your bill.