Waitstaff put in more time bringing food (if they do that, but tips are pooled anyway), topping off drinks, handling odd requests, and then handling checkout. They also make $2 an hour while the person handing doughnuts gets at least minimum wage which seems like a good justification for hitting 0% at the bakery register.

You're right about bartenders being the exception. That I tend to view more as a outright bribe for better drinks and faster service which is honestly not ideal either.

I do think businesses are taking advantage of our guilt and conditioning to try to normalize tips where they never existed before. Hopefully your friend can be brought around to see that. The fewer people who accept it, the slower it will spread. I really hope "tip creep" pisses people off enough that we start to question the entire culture of tipping.