Maybe at some size corporations _should_ become public entities to avoid dragon disease and only those corporations having the means of production. After all, they did grow enormously big by consuming public resources and labor.
So these companies exist in a different reality where they draw their resources and labor from somewhere else? Where else would labor come from if not the public?
Neither are the things in question, the resources for movie making are not public, crew isn't public, actors aren't public. It's not a public resource in any way.