I've noted that most replies here don't mention a tip in the pricing of their local favorite place. I assume very few of us leave 20% if service was good?
I don't know many  waitresses that drive Mercedes or Teslas. It can be tough work for relatively low pay. I also don't think it's expected to tip fast-food service.

Like a few others here, I remember when McD burgers were $0.15 and their price stayed pretty consistent because it was part of their building sign. A full bag of White Castle sliders (12) was $2 or less.