Costco requires a membership. Everything you buy is tied to your membership card. Apple retail stores, let alone Best Buy, do not have memberships. They can track purchases from a credit card, which is why in the original post they apparently required one for identification; but there is no paper trail for cash purchases.
I didn't suggest there was, the issue was whether they could track the sales. In the case of the iPad and or iPhone they usually have to be registered with iTunes to work easily, and guess what that means?