I used to work for a publishing company. No other platform or vendor made us bend over backwards like Amazon. We had to give them the usual non-competitive list pricing that other vendors demand, but we also had to give them a massive, absolutely disproportional cut of the sale price, regardless of profit margin. There were launch date rights they demanded, massive periods of exclusivity for audiobooks in order not to be a second class citizen, total refusal to negotiate terms, etc.

We were not a small publishing house, top 10% by volume nationwide, and (mostly) not paperback trash either. You've probably seen our cookbooks. Didn't matter. They treated us exactly the same as they would an amateur author writing unedited self-pub romance novels. No regard for quality, rating, volume, or any other metric, all must bow before Bezos. Amazon takes such a chunk out of the publishing industry, it actually has a bit of a chilling effect, because you can't afford risk a flop with the tight margins Amazon affords, and you probably need Amazon.