This is not "employees are greedy, want money for nothing". This is a case of "employees barely paid enough to get food each week, survive off tips".
People forget that minimum wage comes out to around $15k a year. Even $15 an hour is only $30k. In almost all of the country, that's not enough for the cheapest rent, upkeep on a cheap car, food, taxes and other bills.
Excessive tips are the only way a lot of people working in the service industry survive at all.
I hate it, it's a sucky system. I would much rather have their wages be higher and the base product go up a bit in price and then remove tipping from most of these industries altogether. But that's just not happening.