I think the problem here is that US lacks a larger framework how unions and employers should solve differences.
Sweden enacted in 1938 (Saltsjöbadsavtalet) a treaty where unions, employers and the government came to an agreement that agreements between unions and employers should be done without government interference. Instead of conflict try instead to find common ground where both parties benefits.
It is of course far from perfect, but I think it is still better than the alternative.