It’s configurable by the business, and you know exactly why they do it, to subtly push people to pay more money. There’s plenty of counter service fast food restaurants where I would never even think of giving a tip if paying in cash, but when the Square terminal prompts me whether I want to leave a 15% or 20% tip and then I have to go into “custom” and type in 0, I feel like a jerk. I know they’re just manipulating me and I hate it, but you’ve got of assume that they make significantly more money that way. Recently I’ve seen more and more restaurants adjust the default tip amounts higher, one of my favorite cafés in North Beach recently changed the settings on their Clover point-of-sale system so the tip options are “20% okay service”, “25% great service”, “30% amazing service”, and “(other)”. It’s infuriating.