I hadn't put in that it was an onion yet.
Before, I'd looked through the options -- choose item by picture, choose an item not pictured -- and not seen Walla Wallas as an option. That's when the system asked for a look. Somehow it recognized the onion.
How did that work? Is there a video camera and a visual database of unlabeled items that the system uses as a backup?
Maybe. It also meant that I didn't need help from an attendant, though the U-Scan seemed to want to send an attendant to me. (It told me a couple of times to wait for an assistant, then reverted back to the "Scan Next Item" step so I could keep going.)
Should I be worried about the intelligence of a U-Scan?