I’m not making excuses for them.
Alot of those jobs are very specific, and highly specialized. If you’re a riveter, then thats ALL you ever do, is put rivets in metal.
I doubt your average machinist has alot of broad-based technical - engineering type knowledge.
I think it simply came down to this. Anytime a new plane model is about to begin assembly or the first delivery is about to occur, the unions like clock work make massive payroll and benefit increase demands, and if they don't get them, they strike. They know its the time when they will have the most power. You can set your watch to this. The strikes last year, which included the machinists and engineers, pissed off and spooked many frustrated Boeing customers. When the unions refused to a strike ban which would cover most of the years when the bulk of the current 787's on order were to be delivered, Boeing knew they needed a 2nd line in a non-union location to keep planes being delivered if the union goes on strike again. Oh and they will strike again.