Why a link, and not a card reader

A United Kingdom card account cannot tap in Portugal. The provider declines the transaction on detecting a different country, and says so in those words. A card reader bought for the event would have been a box that says no, in public, to the first person who tried to pay with it.

A payment link is an online payment. No cross-border rule applies to it. The buyer opens their own phone, on the provider's own page, and pays. Nothing on this site ever sees a card number, because nothing on this site ever handles one.

So no card reader was bought, and the four codes on the cards are four links. {{claim:card-reader-refused}}