I would say that the reality is somewhat looser. Their investment in easily in the 100s of billions. At that price, replacing workers should a strike be called

I would say that the reality is somewhat looser. Their investment in easily in the 100s of billions. At that price, replacing workers should a strike be called is pretty feasible. Unions can, and often do, overplay their hands when negotiating. Adversarial systems, and competitive unions force unions to demand best of industry contracts at every corporation they go to. To draw a football analogy, every unions wants a Christian Kirk contract, and every contract after that must be a Christian Kirk^2 contract.