Unions can make sense for talent and services that you don't want to keep on your payroll full-time. You could argue that rideshare drivers qualify in that sense, given that the whole idea is to keep them off of a regular payroll... but watch them fight tooth and nail to lock out autonomous operators like Waymo. That'll be next, rest assured. It'll be about "jobs," "safety," and probably, somehow, "the children."

Otherwise, the people you list are very well-represented by private agencies. Unions like the SAG can benefit the lower-level people in some respects, but they mostly serve to gatekeep their industry and encourage films to be made outside their jurisdiction.

The person I responded to said "good employees" are inhibited in "growth and innovation" whenever they belong to a union. A single counter-example, of good employees with talent and innovation, reaping tremendous personal rewards, is enough to falsify that statement. I gave several such examples.

On the other hand you have retail workers and food service workers, who are largely not unionized. So what can we blame their low pay and status on?

Talent and genius and innovative ideas being rewarded (or not) is largely orthogonal to union membership. It is a factor of demand and supply, and prevailing profit margins in that industry. That is all.

Detroit declined because factory workers are more fungible than movie stars. Their unions didn't pay attention to the threat of foreign labor or competition by superior foreign firms. Their management also became complacent about competition and chose to blame it on unions.

Germany is very famously pro-union and boasts a strong auto industry. What did they do differently?