I'm from Ontario, Canada, which has a similar but maybe not exact tipping culture.

Tipping at nicer coffee places (i.e. where they offer espresso-based drinks to order) has been a thing for a very, very long time. I can't recall ever not seeing a tip jar and have been going to places like that for probably 25 years, although if you told me the expectation was stronger nowadays that wouldn't surprise me.

The low end places (Tim Horton's up here, I guess Dunkin Donuts would be the comparison), don't expect tips or put out jars / enable them on their terminals, but Tim Horton's has always had a charity jar at the counter anyway so I would think most people would prefer that one.

Yes it started with the upgrade to smart payment terminals, where you insert your card and interact with the screen. It's nationwide now. It got a lot worse during COVID, at which point it became normalized to pay the usual tips even for takeout.

I saw it in Minnesota, Oregon, and DC in 2000-2003… so quite some time. This is barista made drinks, not your Dunkin’ Donuts brewed coffee.

It took the form of a tip jar. It was my main source of gas money when a barista.

I'm living in Ohio and visit two coffee shops on the regular with electronic iPad checkout. One has a tip in the checkout process while the other does not. In the tip included location I've seen people in front of me tip 20 to 30% on a regular basis for everything from drip coffee to the coffee milkshakes that everyone seems to be overindulging on these days. So people are willingly paying $8 to $10 of Ohio money for a coffee milkshake, or $5 for drip!

The Pulp Fiction shake quote always comes to mind for me:

Vincent: "I gotta know what a five dollar shake tastes like"