Yesterday, we told you about the California man who, in spite of being aware of Costco policy when he became a member, refuses to show his membership card when he enters the store and makes it impossible for his receipt to be checked on the way out. Today, someone who actually worked at Costco writes in with a rebuttal.

David says that during his time working at Costco while he was in college, he spent time at both the entrance and exit, and claims that these store policies are often more to the customers’ benefit than they are about security or loss prevention.

He writes:

The main reason for having people show their membership cards at the entrance? To make sure you have one. If you get all the way to the register without your membership card it makes for a serious slowdown since a supervisor has to look up your membership number – you’re not only inconveniencing the clerk at the check stand but everyone who got in line behind you as well. If you forgot your card the front door person will send you to the membership desk where they will look up your membership number and write it down for you so the person at the check stand can enter it in. The registers WILL NOT start a transaction without having a valid membership number first.

The author of the piece we wrote about yesterday was so unhappy with Costco’s receipt-checking policy that he says he deliberately leaves his receipt at the register so that it can’t be checked on the way out.

But David writes about the receipt-checking policy:

To my mind it’s really not just to stop people from stealing. I hardly ever saw people that had items that had not been paid for. Literally maybe once or twice in a month of working the door. We would catch hundreds of dollars a week in overcharges, though. Imagine if you’re shopping at Costco and you bought a giant can of Nestle Quik (this actually happened once) but got charged twice for it. That’s another $10. In that case we would either get a supervisor to refund your money, or send someone out onto the floor to get another can of Nestle Quik. With the kind of volume Costco does errors are frequent and sometimes just can’t be helped. The scanners are so sensitive that it’s really easy to accidentally scan something twice and not notice.

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.

Even without David’s insight, thousands of readers voted in yesterday’s poll that the angry Costco customer isn’t behaving appropriately. More than 90% of voters say he knew what he was getting into when he agreed to be a Costco member. Around 6% say that even though the shopper is correct about his rights, there is no need for him to be rude to the store’s employees.

We always love to hear stories from people who have been on the front lines of retail and customer service jobs. So if you have an experience or information you want to share with Consumerist readers, let us know at tips@consumerist.com

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.