In the US, the IRS assumes you make a certain amount in tips if you work in a job that customarily allows tipping.

So when a customer doesn't tip, the waiter still has to pay taxes on the money you didn't give them.

But wait, it gets worse (this being the US):

Some states allow paying waiters less than minimum wage if tipping is customary. As low as $2/hour.

So a waiter could actually end up owing more money in taxes than what they made that day. All this, and no health or dental insurance, or pension.

I could go on, but you get the idea.

Actually, I will go on. Since most states are at-will, you can be fired for any or no reason at any time.

But just as common, the restaurant manager will threaten you with reduced hours if you call in sick, or get a customer complaint (ie. "My spaghetti wasn't al dente. What's wrong with that waiter today.") Or if you don't do the manager "favors" (see the Chipotle scandal.)

BTW, a couple days ago I was wondering how esperate people would make a living during the extended lockdown. Then I saw the HN submission for OnlyFans ...

Welcome to the USA!