Berlin is a story for itself.
The mainly low houses there results from fire service laws from a hundred years ago, when the fire ladders were short and fire in higher houses could not have been extinguished. :)
But it seems as if they want to change this soon, as there now exists a lack of free spaces for new houses.

But for Germany there could as well be stated, that there exist states like Mecklenburg, theoretically having enough space for every single inhabitant to have an own house. If building them would not be so expensive, of course...
Sadly, those 3D printed houses would not be a solution anyway, as every house to be built in Germany has to be approved by state officials in advance (in terms of safety, ecologic impact etc.) and those officials would likely never allow such houses, I guess. :)