The common explanation for this is that the content owners did not let them. Terrified of what iTunes did to the music business, they cut deals with not-Apple t

The common explanation for this is that the content owners did not let them. Terrified of what iTunes did to the music business, they cut deals with not-Apple to prevent a monopoly from becoming more important than they were. I don't know how to prove that, but it's a story that resonates. For a while I bought all my music exclusively from iTunes but now I subscribe to three different video services.