they can, and many try, but for the most part people don't buy books outside of their chosen e-reader platform (ibooks, kindle store, kobo). Amazon has signifi

they can, and many try, but for the most part people don't buy books outside of their chosen e-reader platform (ibooks, kindle store, kobo). Amazon has significant value to add that they've built up over time and that publishers can't easily get: recommendations, integration with e-reader devices, a huge amount of traffic, and a huge number of people with one-click purchasing already set up.