There’s handheld machines now at American restaurants which have a very bold tip screen. At the one I see it at, the waiter (who usually only took our order, didn’t even fill drinks, bring food, etc) holds it towards me and says “tip?” instead of the common “it’ll ask you a few questions”. Maybe it’s a clover POS system?
Handheld POS terminals exist in America but I found them to be rare. When I was in New Orleans last year and went to a bunch of restaurants, 9 out of 10 of them had the traditional opaque payment system. Only at one restaurant did I I experience the waiter bringing the wireless POS to my table.