Sure, if I am staying in the establishment for a bit, they’re serving me repeatedly by themselves in glassware, offering samples of drinks I haven’t tried, making suggestions, etc. I’ll typically tip $1–2 per drink for that.
If a barista served me over a couple hours with nice mugs by themselves, I’d probably tip as well. But if I’m waiting in line, then give an order to one person, and have my name called out later by a different person who serves me a drink in a disposable cup, that’s not like bartending. That’s the model of Chipotle and Subway, and nobody tips at Chipotle or Subway.
That’s a lot of caveats. So you’re saying there are situations where you’ll walk into a bar, buy a beer, and not tip?