Those workers never had a choice. If it "works perfectly" then why do workers that do have a choice consistently choose to work in establishments where tipping is the norm? That's not a very convincing argument.

The bottom line is that it is the workers making the choice you disagree with, in pursuit of their own self-interest. It would be one thing if choosing one policy over the other was revenue-neutral to the restaurants and workers, but empirically that is not the case.