The thing about GTA is how they would make a movie that appears distinct than your regular crime or action movie. You could say the same for Red Dead about differiating itself from a "regular" western movie, but Red Dead is much more plot-focused and has a much better story, so just "copying" the story would be enough to make an epic movie or movies.
GTA is a big satire on american culture much more focused on the fun and humour, which I find more difficult to adapt and set itself apart from other comedy-action movies.