Because the right to strike is written in the constitution. Postnord isn't really in the wrong here, but instead it's the Swedish DMV that has a questionable in

Because the right to strike is written in the constitution. Postnord isn't really in the wrong here, but instead it's the Swedish DMV that has a questionable inflexibility of using something else than Postnord. The state is not supposed to partake, intentionally or not, in this "game of chess" between employers and unions.