It's a collective action problem, a massive scale prisoner's dilemma where if everyone cooperated we could be in a better world but that just sweetens the social rewards for those who turn traitor and keep paying the tip. And if we collectively do not hit the "tipping point" and force employers to pay better then the employees just suffer. And in the mean time I enjoy a meal that is cheaper than the market can bear because the whole system is propped up by this system of cost misdirection that I have sidestepped. So I am getting an unfairly cheap meal.
No one is worried about Grandpa's opinion here.