refund
It seems reasonable. If you buy a book, and find after a few pages that is not to your liking, you sould be able to reduce your cost via refund.
It is possible that Amazon wants to refuse a refund and since they know you have only read very little, give very little to the author.
In fact, if Amazon wants to only give a proportionate amount to the author, then the purchase price for the book that did not hold you, should be refunded.