Why is this a big deal with publishers? Fiction books are usually valued at a dime a dozen. Textbooks are unsuitable for ebook readers. Selling quantity at lower prices helps drive higher sales.
https://digit.hbs.org/submission/bez...shington-post/
It worked for WP. And like the users say, there is NO reason not to sell on amazon. Natural monopolies (not forced by the government) don't last long usually.