I bought stamps at the Post office today and saw that they have new terminals for swiping credit cards. It was this one, or one just like it.
Perhaps because I was looking at the pen, but I tried to swipe the card in the slot just under the pen. But that’s not where the card goes, that’s just a space between two parts of the device. The card goes in the space just above the keypad (which wasn’t lit up when I used it).
The funny thing is that the clerk said that I wasn’t the first person who did that! Maybe a little usability testing would have helped.