Vice corespondent Matthew Gault has an interesting article about Amazon’s virtual monopoly on book distribution and online marketing platforms: https://www.vice.com/en/article/wxqkx5/book-publishers-warn-congress-amazon-is-too-powerful

“In a letter to Congress, the Author’s Guild, American Association of Publishers, and the American Booksellers Association warned that Amazon has become too powerful.”
[…]
“Amazon’s scale of operation and share of the market for book distribution has reached the point that no publisher can afford to be absent from its online store,” members of the Association of American Authors, the Author’s Guild, and The American Booksellers Association said in a letter to Rep. David Cicilline (D-RI), the Chairman of Congress’ Antitrust Subcommittee.”

Jpegs below of the PDF letter (link above):

Supplemental material: https://www.vice.com/en/article/akz48p/jeff-bezos-has-no-idea-how-often-amazon-rips-off-its-sellers