Disney has their own digital format. They are not working with Ultraviolet. Apple also has it's own DRM format and has not expressed interest in supporting UV. A big reason is that they don't make money doing that. It actually adds costs for Apple. It's a little like a restaurant not permitting you to bring in food from somewhere else. Also, the studios like that apple charges more since they get most of the money based on typical revenue share agreements. If the studios had their way, all digital media would be more expensive.
Some broad points here, mostly for the thread.
1. Even though it impedes fair use rights, encrypted disks are legal, as is the DMCA which prevents circumventing encryption. The loophole is using the analog out from a DVD/BD player and reincoding it as a digital copy. That's why modern players cripple the analog out to a max resolution of 480p. That to me is the most irriating development since it stops me from using my component out ports to my HTDV which eliminates HDCP problems and actually has a more reliable video picture in my application (a long distance between the player and display). I'll add that most people would never bother going to the expense of buying an encoder to make a digital copy that way.
2. The reason there's a hodgepoge of differing rights depending on the title is that the studios are not aligned on how to implement digital rights. It creates confusion and it's reasonable to complain about it, but it's the way it is.
3. If you want a title to work on itunes, buy it through itunes. It will work beautifully in the Apple ecosystem, but nowhere else.
4. Blu-Ray is less compressed than digital copies, even from iTunes. If the quality difference matters, then Blu-Ray is the best you can get, except for a few 4K titles out there via Sony that requires very expensive hardware and a lot of bandwidth to download.
5. We can complain all we want, but the studios produce and sell the content how they like. It's really up to us to decide what restrictions we'll be willing to accept and pay for. Don't like it? Don't buy it.
