When I was younger, 10% was “standard”.
And tipping at coffee shops, McDonalds, etc. is just showing how weak and easily intimidated you are.
When I was younger, candy bars were 5¢ and 10¢.
I have a friend who started as a waiter when he was 16 years old. He’s worked his way up to some pretty decent high end restaraunts. He makes very good money on his tips. Like $300-400 a night during the week, and more on weekends.
It’s late nights and it can be tedious. But if you are good and working in the right place…you can do OK.