I think the issue is that the extras have to have trust in ALL of the production companies involved to not misuse that data in the future. Why pay for processi

I think the issue is that the extras have to have trust in ALL of the production companies involved to not misuse that data in the future. Why pay for processing power to create a sea of extras when you have the full body from your previous 25 productions? "I'm sure no one would notice... Let's do it just this once." Although clearly even if it is codified in the union contract it just adds a layer of security for the actors... they still have to trust the production companies to do the right thing.