As mentioned in a lot of industries outside of restaurants people behave the same way even though it's not true. A lot of restaurants pay at least minimum wage, and not all states allow lower minimum wage, yet the culture is EXACTLY the same. Plus, anecdotal, but I know plenty of folks who will fully admit to tipping because they feel it makes them better people (though not in those words). And try never tipping for a few weeks, you bet your ass some people will try to make you feel bad. I've seen people genuinely forget and the servers would run out of the restaurant to tell at them.
Yes, in some industries people are paid less than minimum wage but the culture would be the same either way. It's also a chicken and the egg situation.