Rich people don't. If you spit in their food and they get sick they'll just get cured by the doctor and then sue the business and make even more money.

If a restaurant starts treating them badly because they don't tip when they come in, they can use their assets and connections to buy that restaurant and fire everybody or just build a spite restaurant next door to steal business.

The wealthy also have a scummy no shame predisposition because most of them are sociopaths who had to climb the ladder by screwing people over and often being cheap or outright not paying bills at all.

I know a lot of rich people who are basically like Ebenezer scrooge, and they look down at the lower classes as being subhuman and not even worthy of a tip. And their mind if you're working that job you deserve your fate because in their Ayn Rand world it's a meritocracy and those who don't have wealth deserve their place in life because they have nothing to offer to society. These same people are often Hypocrites as they stole or inherited a lot of their wealth.