I fail to see how any of this "open contract" stuff is actually needed in the entertainment industry. I can see why in sports, Because sports federations have an in-built mechanism for drafting and trading players between franchises, so it makes sense for that information to be available.

The entertainment industry? not so much. That's entirely between the talent, their representation and the studios/labels. If you want a more nuanced and informed opinion on the matter, i'd recommend watching some interviews with Prince after he got his name back and started his own label. Yes, Labels can really fuck with an artists money, but in plenty of instances it can be beneficial to the artist depending on where they're at in their career.