Ah…part of one of my jobs is to deal with barcodes and get them “in the system.” Actually, this is not surprising that it works, and is probably used regularly around the world. I’ve done cashiering, years ago, and it’s a pretty mindless, mind-numbing job. You end up going on autopilot until something interrupts your momentum: a question, something isn’t in the system (barcode doesn’t ring up), a spill, etc. This is a little more reasonable to me than the cashiers whom accept photocopied traveler’s checks and $3 bills.
Nut - Each item with a barcode has a unique number to it, so that it is identified correctly and the proper amount is charged. There is a server somewhere that has a database of the barcodes, so when read, it reports back to the cashier station the amount. These guys photocopied another item’s (legitimate) barcode, and pasted over the calculator barcode, so that when it was scanned, it came up as another item entered as $10. If they were smart, it was another calculator, but could have been anything.