When I’ve gone to CostCo, the only thing the people at the exit did was to count the number of items you had and to see if that more or less matched the number

When I’ve gone to CostCo, the only thing the people at the exit did was to count the number of items you had and to see if that more or less matched the number of items on the receipt. That seems like the simplest possible check they could make regarding the checkout process.