I doubt most North Americans need a 400A connection. (How much wattage is that? 48kW?) I live in an ordinary single house in a boring suburb in the bay area, and on hottest days, if I have to use the A/C, the oven, and the dryer at the same time, maybe it would push it over ~10kW. Maybe once in a year.
There are places where we waste energy because we're doing dumb stuff: in northern parts of the country, your house should be well insulated and designed for cold temperatures.
Then there are places like Nevada, which are just not suitable for large-scale habitation. "Can we make this monument to our hubris more energy efficient" is kind of missing the point, right?
True, most places would need to run A/C or heater much more often than California, but I doubt they need three times as powerful an A/C at any given moment.
