Could Amazon deKindle returned books?

When I buy a physical book from Amazon, they helpfully offer to sell it second-hand for me:

For Kindle editions, there is no First Sale Doctrine, and no physical book for me to resell, but they can make it go away and give me a refund. So how about Amazon learns from its newly-acquired Zappos's 365 day return policy and lets Kindle users return books they don't want? That could justify keeping the remote deletion feature on the Kindle.