Speaking for America, where it's common to pay by card, I have never had a waiter bring a terminal to the table.

They take your card away and bring back a card receipt for you to sign & leave a tip on.

In Europe, pretty much every restaurant, and many bars and cafés, have portable card readers. (If they don't, then they don't take payment at the table.)

There is no practical alternative, since the customer needs to input their PIN.

Dishonest waiters used to be considered a common way for card details to be stolen.

Example: https://www.paymentsense.co.uk/card-machines/portable/

Numerous large restaurant chains in the US (eg Olive Garden) have installed small interactive screens at every table that act as a terminal, that do other things including take orders. When your meal is finished you pay by card at the machine and leave (it prints your receipt as well). I would expect this premise to essentially spread everywhere among non-fast-food chains.

The mobile card readers are very uncommon in the US. In Canada, they're everywhere.