What's that got to do with anything? Card details aren't stored.
I don't know if they store the card details directly or if they store a hash, but they certainly have a way to tie your credit card to the video of your face leaving the store and (most likely) a video of your license plate as you drive away.
Sell that to a data broker (as they certainly do in the US) and someone could potentially purchase a history of what you bought anywhere and when.
The payment terminal is essentially not actually talking directly to the POS except to tell it that transaction id "xyz"(which only your bank/"card issuer" know is you) was approved, everything else is encrypted between terminal and payment processor and not supposed to be visible to the retailer.