[kaashif]

Yes, but in the US, the waiter taking the card out of your view, doing something with it, then bringing it back is the norm.

I'd never seen a restaurant do that in the UK.

I think it's a relic of the times before handheld payment terminals existed.

Also, having to decide on a tip percentage directly in front of the waiter is awkward sometimes, doing it the US way avoids that. Tipping is very common in the US.