Walmart have been trialling a mobile app in 200 stores which allows you to scan products while you shop, bag them after you scan them, and then pay at the end of the visit without having to ring up the items again at the point of sale. The customer does all the scanning during your trip, then at a self-checkout they pay which involves scanning a QR code and then choosing your payment method. Not yet a total success, Walmart are said to be working hard to optimise the experience to make it a real success. Perhaps having to pay up at the till doesn’t mean you really save any time.