There's just a threshold of utility that has to be passed in order for a new standard to take hold. How much would the US really benefit from switching? How much would switching cost?
The efficiency gained wouldn't come near to the efficiency lost during the switch, and nobody really cares all that much about paper size.
I'm not making the argument that the US should switch (though I wish they would), I'm just stating that the advantages are deeper than they appear at first blush.
The efficiency gained wouldn't come near to the efficiency lost during the switch, and nobody really cares all that much about paper size.