The adversarial relationship was basically the publishers' choice.
Remember that Amazon was willing to basically treat eBooks like normal books - negotiate the price they pay with the publishers and then sell the books at whatever price they want. The publishers are the ones who forced the agency model where retailers are forced to sell at a set price.
That’s one way to describe it. The other way is to say Amazon used their outsized power in the book world, including disallowing pre sales and delaying shipments of regular books, to demand a price from the publishers.
It took a bunch of public pressure to change that arrangement.
I think you can easily say the publishers have bad ebook pricing strategy but Amazon certainly wasn’t using normal market practices for setting prices.
Remember that Amazon was willing to basically treat eBooks like normal books - negotiate the price they pay with the publishers and then sell the books at whatever price they want. The publishers are the ones who forced the agency model where retailers are forced to sell at a set price.