This story is funny. Disney had to navigate a legal IP minefield, when making “Oz The Great And Powerful”.
The original Frank Baum books are in the public domain. However, the original film is still copyrighted and owned by Warner Brothers.
Disney could use the public domain books as source material. However, they had to be very careful to not make their film look like Warner Brothers’ film. Every detail had to be carefully considered to be non-infringing. That included the color of the witch’s makeup. That included the hairstyle for the munchkins. If it was too close, they would risk a copyright infringement lawsuit.
By making a still-copyrighted film, Warner Brothers effectively extended and now owns the copyright to what should be a public domain work. Even though the book is public domain, you can’t make a film that looks like the one that was already created.
Intellectual property is not property. It should be legal to make a book or movie based on any story. Unfortunately, the State media cartel has lobbied for retroactive copyright extension, ridiculously high penalties for infringement, and severely crippled fair use. If I wanted to make and sell my own Star Trek or Superman movie, that should be legal, but it isn’t. Almost everything that was written in the past 100 years is copyrighted and owned by some corporation. That’s a huge cultural loss.