Your view is a bit myopic as you seem to assume Apple can just throw its weight at it and that winning in the US market would be the same as winning globally.
Books are one of the oldest media around and as a consequence most jurisdictions have fairly extensive and specific laws around them and their authors' and publishers' rights. In many cases copyright itself is ultimately based on laws created to deal with authors and publishers.
Infamously, Amazon tried to snub book pricing laws and lost. Google got into hot water with newspaper publishers because its news app violated laws originally written for citing physical newspapers.
This is like suggesting Spotify just ignore the RIAA or Netflix should just stream all content in all countries, licensing restrictions be damned.