Hi, I live in europe, and am not familiar with visa gift cards in specific. Would you mind describing exactly how they work, what form you buy them in, and how you use or enable them?

I.e. is the code printed at the time of buying? Or does it have a scratch-off code and packaged in plastic wrap? Is it scanned under a device while selling?

Even if there dont seem to be any unique codes, an IR fluorescent barcode could be used on the card, or its plastic wrap.

Even if there are no unique codes, the cards might come from a rack or pack in sequence, and the cashier instructed to scan a new pack of cards when opening a new pack!