Costco receipt checking is about catching overcharges

Why do receipt-checking stores do it?

Since the days of Fry's Electronics I'd often wondered if paying receipt checkers was really more profitable than just letting the small shoplifted items go.

I had no idea, but it seems like common-sense now, that stores with miserable return and remediation policies would benefit from up-front attempting to keep you out of them. Having seen both Costco and Fry's return lanes it makes sense that you'd want to catch common mistakes before you let the customer out the door and into the hell of needing help.

Consumerist shares the response of a former CostCo receipt checker to some recent news about a poorly behaving customer (surprise!):

The exit door procedure I would usually follow was to check the receipt for multiples of the same item and make sure they were there. If they didn't have a lot of items in the cart we would just look at the "Total number of items" shown on the bottom of the receipt, count the number of items in the cart and make sure that matched. We weren't trained to catch shoplifting, we were trained to make sure that people were not being overcharged. During the time I spent receipt checking I probably caught well over $1000 in overcharges.