AFAIK OverDrive has quite a bit of vertical integration - they provide the app for end-users, the hosting for books and audiobooks, and a marketplace platform f

AFAIK OverDrive has quite a bit of vertical integration - they provide the app for end-users, the hosting for books and audiobooks, and a marketplace platform for libraries to purchase publishers' offerings (which probably involved many contracts with publishers). By having all of this and being one the first on the niche market, competing with them would be difficult.