On Amazon if I get something (a shirt) and when I get it I realize that I simply don't really like it, I can return it and they are more than happy to take the return. Same with Zappos or other companies that are generally excellent with returns from customers. But the reason they are cool with it, is because there is a large chance you'll deal with them again. A small loss in trade of happiness for likely future purchases.
But being one of the thousands of vendors on Amazon, I'm guessing you don't have this outlook. I personally can't remember the name of a single Amazon vendor I've bought from. I only buy from them if there's either no other options, or if they are offerring significantly cheaper (even when factoring in Prime shipping, which few of them do) than Amazon themselves.
Another thing it brings up is why these companies sell books for 16 cents, or even less to begin with. Clearly, that can't be a way to make for successful business, so like sellers on eBay tried many years ago (and still some today) they are trying to make up for it on shipping fees, in order to beat out competition and likely to avoid giving Amazon a cut.
I don't think Alex is being unreasonable, given that the standards of the Amazon storefront are such that allow for such. On other storefronts, it would be less acceptable. I don't think trying to return an item in an eBay auction for example that is in perfect condition and as-described in acceptable. Yet on Amazon, it would seem to be an ok thing to do. Just as there are social norms, there are corporate norms, and being in a storefront like this carries those norms.