https://help.moviesanywhere.com/hc/en-us/articles/1150052819...
https://www.cnet.com/g00/news/apple-itunes-airplay-2-coming-...
Apple Music's recently released web portal uses Widevine to do DRM (same as Netflix and Spotify web) https://tools.applemusic.com/en-us
FairPlay on Android surely has some bugs if this is the case ...
They did, they commented that iTunes had better streaming than Vudu:
"The system is way more stable at higher quality than competitors like vudu..."
Most people are not apple fanatics. Most people do not need to purchase the movie and value "portability" of such digital format. Most movies are not worthy of repeat views, esp at different locations. Most people do not differentiate that much between HD and 4K when watching at home, on a setup that is not a home theatre.
People don't decide which platform to purchase a movie from based on how compelling the streaming technology is. It needs to be a platform that's accessible on their device firstly.