The news of Amazon's new "unlimited library" or "Netflix for books" service broke after I posted on Friday.
And one of the first things I was asked was why only some of the anthologies I'm in were on it.
So, I'm going to explain a little bit about how it works from the author/publisher side of things.
Kindle Unlimited works fairly simply. Amazon sets aside money - at first from their capital, and presumably eventually tied to the number of subscribers. Authors/publishers get a percentage of this fund prorated to how many times their books are borrowed.
It's potentially a good way for an author to be found by new readers. However, there are some roadblocks.
The biggest is that to enroll your books in Kindle Unlimited, they have to be in the Kindle Select program. This means that the electronic version of the book can only be sold through Amazon. The Select program has quite a few perks associated with it, including Amazon taking a lower commission on sales and some free promo stuff. Some authors/publishers, however, feel that those perks are not worth the price of limiting their books to one ecosystem. Being in Amazon Select means your book is only available in .mobi format, which is proprietary to Amazon. This is a fairly small deal as any phone can read .mobi books (I have the app on my phone myself, as my ereader is a Nook). It also means that you can't sell through other outlets and, which matters to some people, you can't sell to traditional libraries - libraries purchase their ebooks through other systems. If you are an e-only publisher, this is a big deal.
Additionally, a few authors don't like the KU terms and are pulling their books out of the system. Others are putting some books in and not others - there's been a fair bit of talk that KU might be a good outlet for short fiction "singles," which are hard to sell.
What it boils down to is that for each individual book, each individual author or publisher has to make the decision of whether to enroll that book or not. It's nothing personal to those looking for books on KU - it's a matter of doing business and choosing the strategy that we think will lead to the most sales. (And this isn't a knock on Amazon either - they too are choosing the strategy they think will make the most money).