The Wall Street Journal reported on the rise of digital, self-checkout kiosks and how customers have responded to tip prompts. Many customers who were asked to tip workers with whom they had no interaction were frustrated with these prompts, per the Journal.
When I was a kid a friend's dad took us to a grocery store that had a gumball machine. We begged for a quarter and the machine ate it with no gumball, so the dad put another in, got the gum, chewed it up and immediately shoved it into the coin slot. This, but for self check out machines