According to the National Retail Federation, shoppers with 50 items in their cart had a 60% chance of having at least one un-scanned item, while shoppers with 100 items had an 86% chance of error [1]. In 2018 when Walmart first introduced Scan and Go, a major reason it was cancelled was theft[2].
Combining the super convienent Scan and Go with RFID will mitigate this problem. Before customers leave the store they just have to place their cart/bag on the RFID system and scan their phone on the machine. If there are any extra items the RFID detects, it will remind customers to scan the items. This will reduce theft and will also be fast, autonomous, and simple.

RFID uses radio waves to scan all objects in the cart at once [3]. However if used as the only checkout method, it can be inaccurate. Thus I propose that Walmart should use RFID in conjunction with Scan and Go to double check the shopper. Right before the shopper leaves they just place the cart on the RFID and quickly scan the machine. If there are extra items the RFID scans that is not scanned by the phone, the machine can remind the user to scan it. This may add just a few seconds to the shopper but save millions for Walmart.