Sven,
Why do the plugs in the US have holes in the pins?, is there some sort of retention system in the socket that mates with this?.
All of our 3-pin plugs in Aus/NZ, have to conform to AS 3112 and as you said, this is a very exacting standard.
Regarding the extension cords, just a simple recess on the cord connector(female Line socket) saves 10 lives per year from electrocution from partly inserted plugs, especially in damp areas.
I know I will sleep better tonight, knowing this statistic!. [Linked Image]