Don't think we've ever seen Hollywood in the modern era without unions, so not sure how you can claim it's "undeniable" the industry is better off. We basically have no clue if it's better off or not. Unions are intended for industries where a worker doesn't have a marketplace of options as there is a single or just a few employers (e.g. Hollywood, teachers, coal mining towns, hospital staff, etc.). Unionizing at Goo…
You have two incorrect assumptions here:
1. Non-union filmmaking is absolutely a common thing. Most crew members start their careers on nonunion shoots. Further, not all filmmaking related unions prevent their members from participating in non-union shoots (though some do and others will encourage you to call the shoot in if the budget is high enough to justify union participation).
2. Most crew on a film are not working for a specific employer on an ongoing basis. Generally, crew are hired on a contract basis for individual projects.