THE ASSUMPTION – Receipt checker = theft check

The person at the Costco exit check is not looking for thieves. And Costco has one of the lowest theft rates in retail. That employee is actually a quality control step. They're catching cashier scanning errors. Costco has done this since the price club days in 1976 and has publicly said it's about scanning accuracy QC. The checkers glance at the cart, glance at the printed receipt, and confirm the item count lines up. And anything off goes to the supervisor for refund or recharge. The payoff: Small % times big ticket. 0.5 to 1% scan errors times ~$150 average ticket times bulk-sized items equals refunds plus margin loss avoided. The math here is that a cashier scanning error rate is run around 0.5 to 1%, which is tiny per transaction, but can be huge at scale because Costco's average ticket is around $150 and the items are bulk-sized. So every mistake, even if it's just a single item, can be expensive. Some errors will overcharge the customer, which means a refund. And some undercharge, which is just direct margin loss. A human at the door catches most of it in about two seconds. Costco tested computer vision and humans at this task, and humans were faster and more accurate at this task. The whole thing is just a quietly clever operational design, not fancy tech. It's just a person being good at their job.