I’m assuming that the GP is an American used to American standards of being waited on (where the staff are incentivized by tips and thus have to impress their customers), and so does not want ”rushed and curt” service to be encouraged (which would diminish their experience), rather than them having an aversion to QR codes per se.

Because encouraging people to be rude to each other is distasteful, I thought it was obvious.

Similarly, calling someone a “low value comment” and then taking the least charitable view of their comment is directly against hn community guidelines.