I don't agree that a tip is a gift. Waitstaff are paid below minimum wage based on the expectation that a tip will be earned. You should always tip except in the rare circumstance where service was intentionally horrible or the was a complete disregard for customers. The pre calculated amount are useful for those who may not be mathematically competent.

I don't see the big deal. It seems like you are making the argument that printing tip amounts is somehow indicating an expectation for something that is optional. However discretionary tipping may be, I think most expect to tip and waitstaff (and the IRS) expect tips will be earned.