They can't implement a service like this in the US until 2024. Literally can't. Many of those movies/shows (Grey's Anatomy is on Netflix, Disney would kill to have it with how popular it is) are tied up in Hulu or other streaming properties under contracts so they need to wait for a lot of that to expire.
The bigger issue though is they have to wait until 2024 before they can get Comcast out of Hulu and until Comcast is gone, there are major restrictions on what they can do in some instances. For example, notice Modern Family just showed up Peacock and Hulu. It's an ABC Signature production, so Disney owns the show, but Universal had the television syndication rights, so Disney and Comcast came to an agreement to bring it to streaming on both services. Disney+ was not on the table as an option (from what I read) in that agreement since Comcast had the leverage.