[anatnom]

The UK also does "chip and pin" authentication for requests, so the waitstaff are forced to either bring a portable cardreader to you or for you to walk to a terminal and enter a code. I think this is why mobile card readers are so common.

In the US, most credit card transactions are simply "(swipe or chip)". If you have the card, you can use it. Gas stations seem to be the slight exception in America -- they generally require "(swipe or chip) and billing zipcode". This is quite funky and not at all secure against fraud.