Business conditions change. Did you notice that GM shut down some of the Oshawa plant? CAW expenses are leading to reduced work, IMO. And look at how many Asian and European auto companies assemble cars in the USA now. They even export cars from the USA.
I read today that the UAW wants to unionize VW’s new factory in Chattanooga. The UAW has had no success unionizing any auto assemblers beyond the Detroit 3. I rate their chances as slim, and Slim just left town. I also heard a few days ago that union members comprise 10% of all private jobs, and just 12% of all jobs (including government). Unions are hurting big time. I wonder if there is anything they can and will do to change that?