My current workplace is one such case of union killing a theoretically profitable company so I really am speaking from experience - the only reason the workplace still exists today is because after it went bankrupt it was bought out by an outsider who discarded the union part. Ironically it turned out to be for the best for both the company as a whole and the actual workers.

Just because you don't hear of it - or don't want to hear of it - doesn't mean it doesn't happen.