I found an article about this.

You're going to have to double check you have your ID on you before making a Costco run from now on. The superstore already requires customers to show their membership cards at the register, but a new policy is geared toward a Costco weak spot: the self-checkout kiosks.

With self checkout expanding quickly throughout stores since 2019, the company has seen a rise in shoppers passing their membership cards to friends or family to use for their own hauls. To prevent this misconduct, Costco has said members will now need to show their card to an employee when going through the self-checkout line—and if your card doesn't have a picture, you may also need to show a photo ID.

“Costco is able to keep our prices as low as possible because our membership fees help offset our operational expenses,” reads a statement from a company spokesperson. “We don't feel it's right that non-members receive the same benefits and pricing as our members.”

On the heels of Netflix’s attempt to eliminate account sharing, this move is yet another example of companies enforcing rules to keep memberships from being abused. Costco has a membership base of more than 120 million, and it relies heavily on these fees—according to its 2022 annual fiscal report, they earned the retailer $4.2 billion in revenue.

A basic “gold star” membership costs $60 per year for one household. You can also choose from a “business” membership for the same price and an “executive” membership, which includes additional perks and savings, for $120 per year.

USA Today posted a query about the new policy in the “Costco Fans Midwest” Facebook group, and enthusiasts had mixed opinions: Some agree the crackdown is fair, but others feel that it’s bothersome to be asked to pull out their IDs at any point—in the checkout line and throughout the store. Ashely Dixon, a shopper from Illinois, commented that she was stopped four times during a recent trip.

“I’ve felt more and more like I’m doing something wrong each time I go,” Dixon told USA Today. “It's annoying to be hounded at every step while shopping.”

Regardless of the new policy, there's no need to give your card to someone so they can save money at Costco—there are lots of ways to share the shopping experience with non-members. In fact, the company encourages it, and even offers hints at how to shop for friends and family.

"The Costco membership card is non-transferable, but there are several ways to share the experience with family and friends,” the company’s customer service website says. “Anyone with a card can bring up to two guests to the Warehouse during each visit. Keep in mind that purchasing items is exclusive to Costco members."

That last sentence is the key to following the rules of your membership: If your bestie wants to split 24-pack of Kirkland Signature seltzers or a giant bag of avocados, bring them along for the shopping trip and let them pay you (or treat you to the $1.50 food court hot dog combo) afterward. Quality time and good deals—it’s the best of both worlds.