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.
But would you lounge on your (or someone else’s bed) with your shoes still on? From the other answers, that seems to be rare or even TV-only.
Shoes on carpets and floors, I understand. That’s how we do it where I came from originally (I don’t do it any more because the climate is different where I live now).