I think the standard for the Swiss plug is from 1959, making it somewhat newer. Of course, this could simply be an update of an older standard.
Well, it has clearly evolved from the old ungrounded system that has once been used all over Europe, 4mm round pins on 19mm centers.
Germany seems to be the only country that ever had ungrounded plugs with 4.8mm pins rated 10A. Austria simply never had any ungrounded plugs rated for more than 6A.
