If anyone has read a critical piece of work on what constraints in Germany allowed unions and companies to co-evolve instead of adopt the adversarial position that characterizes the American interactions, please share.

There is something categorically different and I'm not sure how that came to be.

Edit: I'm rate limited for comments. Thank you, my dude, for the recommendation.

I'm glad you asked! Can't recommend this book enough; it's beautifully written and also short - in matters of philosophy, less is most definitely more. It's a general work on the adversarial legal tradition and while it doesn't touch on German labor unions specifically it does go into some detail about the differences between the (Anglo-)American and continental European approaches.

Adversarial Legalism by Robert Kagan. https://www.hup.harvard.edu/catalog.php?isbn=9780674012417