Have Magic customers been clamoring for Magic's employees to unionize for the past 30 years? This benefit you purport strikes me as purely hypothetical and possibly wrong: if they can't downsize when they need to, they could go out of business completely.

Unions don't prevent downsizing when it is actually necessary. What they do prevent is downsizing to goose the stock price, and that is good for the customer.

GM circa 2008 would like to have a word

I'm afraid I'm not familiar with the specifics. Can you link clear proof that unions were preventing necessary downsizing, and that this downsizing would have saved the company?