Is union recognition legally required to, say, organise a strike? Do workers who participate in a strike organised by a non-recognised union expose themselves to getting fired?
The thing to understand is that labor law in the US was created to "reduce labor strife." Unions existed before they were recognized as legal. What labor law tries to do is make an orderly process with the goal is no strikes and a mutually agreed-on contract.
The company recognizing the union is the first step towards a contract. Basically it's saying "I understand this organization represents these employees and I should negotiate with it."
So as you can see, they have incredible free speech! They allow just anyone to carry out a street march!
Compared to the US where multiple protesters have been killed on video by ICE this year Germany is a dream of free speech