Unions can also receive fines for organizing illegal strikes. Union heads have gone to jail for organizing illegal strikes, but it's incredibly rare and hasn't happed in decades.

I suppose the corollary to my question then is, "What are the traits that an organized strike must have that makes it immoral or harmful to a society enough to enact punitive legislation?"

Simply put, "Where's the line?", as they say. I understand military necessity, but Air Canada is a business, despite being publicly traded (as far as I know).