When I was in the book business, I used to sell books to Amazon before they discovered how to make more money than the sellers. They used to search independent used book sites like Bibliofind and Abebooks. Sellers on those sites could decide if they would like their listings to show up for Amazon buyers. Amazon had buyers to work with each Amazon seller on an ongoing basis. When they saw a book they wanted for an Amazon customer, they would contact the seller that had the books and buy it from that seller. Then the seller would dropship the book to the customer with an Amazon label. It was a beautiful arrangement. We got our full asking price and Amazon got all the credit for supplying the book.
Once Amazon got the basics down for selling used books, it bought Bibliofind and Abebooks. It closed Bibliofind and redirected site visitors to Amazon. Customers ordered direct from Amazon and used booksellers began to experience what you have. I never did sell through Amazon again, though most of my friends did. They sold more books through Amazon, but then could not get as much profit for them as they could through the other sites. I started selling through a book cooperative owned by its members — Tomfolio.com. It lasted over ten years and died when it lost its programmer whose son had died. I had to leave before that because I was physically unable to keep shipping books out and I knew Amazon’s FBA was a losing proposition for me.
I still have inventory, some of it valuable. It would probably sell on eBay if I wanted to ship again. I’m still trying to decide what to do. I appreciate the way you shared your experience. You’ve convinced me trying Amazon is just not worth it.