There are alternate TV dimensions in which all of the TV characters speak one particular language because a certain country at some point conquered the world.
With German Toobworld, that happened with Germany winning World War II. (It was a world in which Edith Keeler survived her encounter with three Starfleet officers from the starship Enterpise.)
For the most part, life in German Toobworld (Earth Prime-Time/Deutsche?) played out the same as it did in Earth Prime-Time.
Here is an example: