Germans. Augenhöhe. More consult than serve. Ok, fine. American customers can work with the German approach. Maybe even work better, if the approach is understood by both sides and is applied carefully.
But even if so, it can look and feel to the American customer as if the tail is wagging the dog. The customer is the dog. The German supplier-vendor-consultant is the tail. Germans don’t want to be the tail. Who does? But the American customer is clearly the dog. And that dog doesn’t want to be wagged by its tail, German or any other culture.