There are a lot of titles that aren't on there for various reasons. Anything newer that might have a streaming deal somewhere else isn't on there yet.
-Quite a few older movies aren't on there (Mighty Ducks, Something Wicked This Way Comes, Dragonslayer, to name a few).
-Controversial titles like Song of the South aren't there.
-I'm sure there are tons of animated shows that aren't there.
-It doesn't have every Marvel or Pixar title either (Incredible Hulk, Iron Man 2, Coco, Up).
Disney owns a lot of stuff, and a lot of that stuff isn't there, but it's easy to find lists of what is there, and I'm sure some of it will come on later, and some of it will probably rotate.