Divide and Conquer
I think region locking DVDs, Games, BD & Geo blocking digital content funds piracy.
The books issue is two fold.
1) A hundred years ago, USA simply ignored copyright on English Language books. The USA and UK publishers more or less "divvy" up the world.
2) A book publisher doesn't usually have audio rights, no more than they have film or TV rights. Nor for worldwide unless not in English (see 1). A publisher of Audio needs to acquire these separately from author.
There is a separate issue that often the Publisher acquires books rights for life of copyright. It ought to be no more than 25 years and then revert to author (copyright would STILL exist and be unchanged from POV of public).
Copyright life is also now too long. Death of Author + 25 years is generous. The current death + 75 is simply a licence for people like Disney or Record companies to make money, as they will have acquired rights with a minimal up front and small royalty on sales (or in case of cinema, maybe profits which are mysteriously non-existent).
Always negotiate a percentage of retail sale, never "profit", accountants are too clever.