And then with scan-as-you-shop (some shops even have apps, I know Asda does) latency is reduced further, it's only the time to transfer you're already scanned basket and to pay
yeah exactly. I guess I don't understand the marginal improvement in adding so many cameras and advanced processing, all so that you can "just walk out", with the possibility of having to deal with billing related customer service issues.
I wonder if it would be possible to integrate payment into the mobile apps they've already got in place, thereby meaning that the only time you'd need to go to the checkout at all would be if you were buying restricted goods (e.g. age limited, or items with security tags) - the risks would seem then to be tracking whether someone had paid. Maybe have a QR code shown on screen which security staff can scan if they're suspicious, giving a list of what items were purchased?
I see a version of the QR code check already in Sams Club. A person at the exit scans your bill and it tells them what to check for. Otherwise they will randomly scan an item and it will cross-check with the bill.