The "good old boys" stereotype is a stereotype for a reason: it doesn't actually happen in meaningful numbers.

If you get paid well, have good benefits, and can't get fired arbitrarily (union still allows for firing based on performance), it turns out your workers will be happier and more productive.

Also, if labor costs (paying a decent wage) tank a massive jet company, they already had many other problems under the hood. Your argument is also proven to be false, because Airbus (heavily unionized) has been eating Boeing's lunch for years since they didn't greedily spin-off everything nor slacked on quality control for the shareholders for short-term gain.