It is also interesting to note that up until the late 50's it wasn't required to earth domestic GPO's if there was no other earthed fittings in the same room.
Actually "isolated location" would still be legal in Germany and Austria, but with central heating it would be close to impossible not to have any grounded metal surfaces in a room.
Austria never really cared about the "no other grounds" requirement much anyway... I've seen loads of ungrounded and Schuko receptacles side by side...
