That's a traditional payment system where you hand off your card to some waiter who then sketchily takes off with it and does who-knows-what with it and returns

That's a traditional payment system where you hand off your card to some waiter who then sketchily takes off with it and does who-knows-what with it and returns it along with your receipt. The modern ones have these portable card terminals that are chip+PIN only. These customers would have to come back another day to pay.