I tend to agree, yet I also believe if I'm not mistaken this is kind of how servers at restaurants work too. They have some minimal base wage, then tips. If their tips do not take them to minimum wage, the employer must pay the difference to get them to minimum wage. In essence, we as customers are subsidizing the restaurant owners to get their employees to at least minimum wage pay. So the question is why are we just now getting outraged when this has been being done to people for a while in certain places, and is still happening to servers but it's somehow not complained about that I'm aware of.
edit: looks like it depends on which state you're in in USA on this. Mostly West Coast seems to have 'sane' ones: https://www.dol.gov/whd/state/tipped.htm