That seems reasonable enough to me though. It should be the publisher's choice what formats of the book they are willing to sell.

Having the action prominent and potentially with the default reversed would still leave it to the publisher's choice.

We can understand why they do it this way (they only need the option to exist, and can afford to apply dark patterns to it), but we don't need to excuse Amazon. Especially when they don't give a shit about what we think in the first place.