If TSOs were permitted to accept a card they've never seen before and weren't trained to verify, such as the HK ID...they'd have to permit other regionally obscure cards, such as Moldova or Zimbabwe. It's hard enough to get them to recognize a US Passport Card! The bored BOS TDC was being lazy, and I agree with the other poster...LAX was right. If your card is not US or Canadian, you have to show a passport.

On a sidenote...Korea, Japan, and Taiwan each have several Costco locations each. I wonder what would happen if someone were to present a TDC with one of those cards...