The entire concept of tipping is bizarre, and is demeaning to all involved.
As an employee, I want to know whether I will earn enough this week to pay my rent; and I don't want to take unpredictable and random pay cuts because the customers I get happen to be having a bad day, or because the cook stuffs up their order, or for any of the myriad things beyond my control that affect how much people leave for a tip.
As a customer, I want to see a price on the menu that is the amount I will have to take out of my wallet. I don't want to have to guess how much to pay, and to risk poor treatment in future if I guess too low; And I don't want to have to carry enough cash to pay for everything, or to pay part by credit card and part by cash, just so I can be sure that the person I am tipping gets the tip.
As an employer, I don't want my staff competing against each other, I want them to work together as a team. And I don't want them to be sucking up to the few customers who are expected to be good tippers, and leaving other customers with a poorer level of service as a result.
The whole idea of tipping as a routine part of business sucks. Occasional tipping for excellent service, beyond the norm, I can understand - although even that has its problems.
You don't tip people who are your social equals. Nobody tips his dentist, or his accountant; tipping someone is a statement that you are of a superior class, and that their livelihood is at your whim as part of the ruling classes - at least, for the duration of your meal.
A minimum wage should be the lowest amount that anyone may be paid. No exceptions, no ifs, no buts.