We travel internationally a few times per year and have come very soundly down that the American tipping culture is more or less a cancer in our culture. It sort of hides the true cost of service, and doesn't
really motivate service workers (after all you can tip in no-tipping countries if you want) but now three things have happened:
1) Tipping is regularly hitting north of 20% -- even for self-service or fast-food type venues. When 1/4-1/5 of your bill isn't figured into the food price, people take mental notice and restaurant patronage is significantly down. Payment processors at POS are also somewhat responsible for this trend, as much of the Tip request process happened by the store, who usually put it as a blank line on a paper bill, but now it's offloaded to the processor's systems and all kinds of nonsense shows up on the Tipping screens.
2) Due to recent rapid inflation, services are trying to "fake it" to keep prices down, but adding in other fees before the tip, which makes consumer costs go up anyways. It's becoming a significant legal problem in many areas when an additional 10-15% "fee" shows up on the bill.
3) Even with tips, workers can't make ends meet as housing and other basic living costs have gone through the roof. There's a nationally recognized worker shortage, and it's because even taking extra shifts and providing exceptional service isn't bringing in enough TIPs to make ends meet, so workers are leaving or switching to other industries. Which makes the service worse when you do eat out.
This means consumers can't figure out how much it costs to eat out anymore. That $10 sandwich and drink combo from 2020 is now $16 + tax + fee + tip = >$20 and now you're getting the same thing for more than twice the price, all a change in the last 2-3 years. So fewer people are eating out.
The food industry is tipping over into a death spiral and it's become time to properly professionalize the service industry and return Tips to a "not expected but welcome" option.