First of all, let’s try to avoid American-bashing, and stay respectful to everyone.
I’ll start: for me it’s the tipping culture. Especially nowadays, with the recent post on !mildlyinfuriating@lemmy.world with the 40% tip, it just seems so weird to me to have to pay extra just so that menu prices can stay low.
I’m American and I don’t know a single adult who does this. Even kids take off their shoes before walking around the house, typically.