Interesting story and the comments are very interesting too. The thing that gets me is that we order a lot of carry-out, like 3 or more times per week.

When I swipe my card, that % option pops up and I feel like a jerk if I don't add on at least a 15% tip to whoever hands the bag of food to me. I scratch my head, recalling when a tip of that amount came after good or at least passable table service with someone bringing your food, filling your water, etc. Now I routinely tip $5 or more for someone handing a bag of food across the counter but, as you wrote, it is basically subsidizing the restaurant owner.

When it comes to a $2 coffee, I'm perfectly fine with tipping a buck or two, especially if I'd be sitting there for a while. I consider it more like "renting a table" for an hour for cheap rather than thinking of it as a 100% tip.