My best guess on this is that it's as simple as 1) most people are not Apple users (harder to reach critical mass online), 2) and most Apple users are aware of

My best guess on this is that it's as simple as 1) most people are not Apple users (harder to reach critical mass online), 2) and most Apple users are aware of other ways to access things if that's what they want, while the ones who don't want that buy Apple in part because of the more walled garden aspects. This is purely speculative though, so it would be interesting to see surveys or other perspectives.