If you buy at Costco, you can return them at any time in the future without a receipt. The return desk will lookup past purchases using your membership card.

yea if it fails after a year (vs. a few days) very few people are going to bother with or even remember there was a warrantee

The advantage of buying online.

Or Home Depot. Give them your email address and attach your cards to it and then you will always have the receipt.