Zero interaction with employees during a transaction no longer guarantees freedom from the moral quandary of how much to tip. From a report:

Prompts to leave 20% at self-checkout machines at airports, stadiums, cookie shops and cafes across the country are rankling consumers already inundated by the proliferation of tip screens. Business owners say the automated cues can significantly increase gratuities and boost staff pay. But the unmanned prompts are leading more customers to question what, exactly, the tips are for. “They’re cutting labor costs by doing self-checkout. So what’s the point of asking for a tip? And where is it going?” says Ishita Jamar, a senior at American University in Washington, D.C., who has noticed more self-serve tip cues at restaurants she frequents.

Tipping researchers and labor advocates say so-called tip creep is a way for employers to put the onus for employee pay onto consumers, rather than raising wages themselves. Companies say tips are an optional thanks for a job well done. Businesses “are taking advantage of an opportunity,” says William Michael Lynn, who studies consumer behavior and tip culture as a professor at Cornell University’s Nolan School of Hotel Administration. “Who wouldn’t want to get extra money at very little cost if you could?” Square, whose technology powers many iPad point-of-sale machines, says tipped transactions were up 17% year-over-year at full-service restaurants and 16% at quick-service restaurants in the fourth quarter of 2022.