I dread the day I have to eat at US restaurants, or even get something delivered. Part of the reason is cultural: I’ve never lived in a country where a tip is mandatory and you’ll be called out if you don’t. The other reason being it involves a degree of social pressure and shame, if one doesn’t tip enough. Both don’t sit well with me. But I can attest that if I’m forced to tip, I’ll not return to that establishment.
I've lived here for a long time, but this stuff still gives me anxiety. I get you are supposed to tip in restaurants, but I'm unsure which other services need tipping. Is it required to tip, for instance, the HVAC repairman? Are you supposed to tip mechanics? Do native Americans have a spidey sense for which people need tipping that I just need to become sensitized to?
The only situation where there is an unwritten expectation for a tip is at a sit-down restaurant with waitstaff and for food/grocery delivery. These are luxuries 99% of the time.
In all other cases that I know of, they will ask you outright if you want to tip. For example, when I get a haircut or a massage, they ask me explicitly if I want to tip, and, because it was a personalized, intimate, luxury service, I oblige. For simple walk-up services like coffee or take out, I wouldn't tip.
The only other times I tip are for exceptional service (e.g. in a fastfood drive through) or if it's a local business that I'm fond of.