What? It has nothing to do with copyright. It's a provision negotiated by unions for the benefit of members which means you can't employ anyone in certain union

What? It has nothing to do with copyright. It's a provision negotiated by unions for the benefit of members which means you can't employ anyone in certain unions without a minimum royalty schedule. Notably, live action productions covered under SAG-AFTRA and WGA get residuals while animated works under IATSE did not until very recently.