@tilton @bytebro @Archie8 @sotneStatue @RoboChimera
The key is in the non-reversibility.
A reversible plug requires a double-pole power switch on the appliance, otherwise one might end up opening the Neutral side of the circuit instead of the Live. Most manufacturers don't go to this expense.
This is why CEE 7/6 is better than CEE 7/4. It's also why 2-pin #NEMA connectors have been polarized since the 1940s.
Don't sell the U.S. short; these NEMAs beat Europlug.