Costco is different. Inspection is part of your membership contract.
Costco is also anti-gun. Has a company policy prohibiting guns on their premises.
They recently threw me out of the local warehouse when my OWB, covered, pistol printed on my shirt. No signs on outside of store, either.
I had been shopping there since 2016 without knowing of their policy. Yes, I spoke to the store manager, wrote a letter to the COSTCO CEO and canceled my membership.
You can find their policy here: https://customerservice.costco.com/app/answers/detail/a_id/709/~/are-guns-%26-personal-firearms-allowed-in-costco-warehouses%3F
Moved to Sam’s club. It is my understanding that their, and Walmart’s, policies are no open carry and allow concealed carry. Go here: https://www.concealedcarry.com/national/walmart-turns-boldy-anti-gun-stops-sale-of-ammo/