I think their biggest ask is for GM to stop using temp workers to get around union obligations. When you have a "temp worker" who has been working for you for 4-5 years, they should probably be classified as an employee.
What about the half of Google workers who are merely contractors?
However that doesn't impact current union employees. Is it just the union fearing for its own loss of power?
In part, though I think it's more complicated than just a loss of power. The responsibilities for employers are getting more and more expensive so they are doing the rational thing and switching to contractors.