Small caveat, but Walmart isn't copying Costco. Sam's Club has always done the receipt checking, too, and Walmart/Sam's Club are owned by the same people. So in a way, they're bringing their Sam's Club behavior over into general Walmart. What makes this infuriating is not only being treated like a thief and having to go through more steps to get out of the fucking store, but I didn't pay for any perks or sign any contract that allows you to search my shit.