Karlsruhe is a city of civil servants, and techies. The local university,
Karlsruhe Institute of Technology is tech only, as the name is meant to
cement. Calling the ground floor "zero" is therefore natural. Next time
I expect the floors above to bear binary number labels.
If this notion fills you with dread, the sculpture at the Frankfurt
airport may be for you. The artist must have been facing a flight
to the USA.