The one facet not present at the negotiating table but surely on the union's mind was the idea that they could play 'chicken' with the company only to stall long enough for Santa to come sledding in to save the day.
Having worked in both union and non-union shops, it seemed to me that the workforce in a non-union shop had a personal investment in the success of the company. Contrast that to a union shop, where the company was often (not always) viewed as a money-tree whose primary purpose was to provide a living to the workforce. Any profit that was turned was secondary to the primary purpose.
I unwillingly participated in one of these showdowns once. It is incredible to watch people with families to feed vote themselves out of a job.