Tipping culture is effectively impossible to tax, anyway. Electronic payments make it easier, but do we seriously believe that people are all reporting their cash tips as income accurately rather than treating it as a windfall?
The only way to eliminate taxing tips altogether is to eliminate their role as part of the income stream and make them optional gifts, which means (1) ensuring that people are paid sufficiently without them, and (2) making them truly optional. Neither one seems likely to happen. The only way to tax them effectively is to record them effectively, which also seems unlikely to happen.
I can’t think of a good reason to stop taxing tips other than the recognition of the status quo, that we’re not really taxing them now. I can think of some nefarious reasons on the conservative side (the wing that wants no floor on wages).