Political flyers seem like something very different to license plates. The court might decide differently under different circumstances.

It's not just random postal workers doing it though, it's union members doing it as part of a sympathy strike. And surely every workers "duty" is their job, so then no striking should be allowed? Or should only complete strikes be allowed?

Union members should be allowed to go on strike, complete or partial as far as I'm concerned.

Has there been a strike against a political party in Nordic union history?

They are not refusing based on content, they are refusing based on recipient – two very different things.

It just so happens that license plates are one of the things that gets blocked. Not because they are license plates but because Tesla is the receiver.