One underemphasized point is that normalized tipping is actually about having customers monitor and evaluate employees and what their wages should be. Similar to how the normalization of receipts became about ensuring that employees working counters could be held accountable to customers, the customers taking in the role of surveillance.

Rather than a form for worker solidarity, tipping culture has been appropriated by capital and turned into a means by which to put a manager's job onto customers, discipline labor, and drive down overall labor costs.

Of course you can't be a Trotsky and undo tipping culture by just not individually tipping, but it should go on the list of things to abolish.