There's a million examples of this but a good recent one is this:

https://www.nbcnews.com/news/us-news/waitress-says-customer-wrote-mask-receipt-lieu-tip-after-she-n1242611

And this is why the US tipping culture bothers me. This waitress is out of money she depends on to live because some asshole maga nazi doesn't like to follow rules outside of the waitress' (and really, the entire restaurant's) control.

If every patron decided to be a piece of shit that day, that waitress would've worked a full day for like $9 or whatever.

That's bullshit.