At least at all the Costcos I've been to in California, you need to first scan your membership card before your payment card. So without a membership card you c

At least at all the Costcos I've been to in California, you need to first scan your membership card before your payment card. So without a membership card you can't even start the process. The attendants can override this I think, but lately they've started really cracking down on this and not allowing it.