Well, during the Seattle "Snowpocalypse" (that is, the few actually cold days in the area last winter), the heater (actually, the AC doubling as heating unit) in my apartment had to work overtime to make up for the bad insulation. The worst offender was the balcony door that was just a normal wooden door with no proper rubber seal around it and even pretty big open gap between it and the floor. The single pane windows probably didn't help, either.
If this is average for the construction in the US, then there is a lot of room for improvement. You can absolutely build lasting wooden houses with adequate fire protection and good insulation. But it seems that there's not a lot of incentive to do so on that continent.
The Pacific Northwest is a poor example there, because as you indicate, the "cold" winter days in the densely populated areas are still pretty mild.
The Great Lakes region of the US (like Minnesota, where I live), and some parts of the Northeast, are places that experience considerably more ... 'Scandinavian' extremes of cold, and the houses are built to handle it.
Well, even the regular winter days are cold enough to require heating. And the generally poor insulation of the building leads to considerable thermal losses even in normal winter conditions.
If this is average for the construction in the US, then there is a lot of room for improvement. You can absolutely build lasting wooden houses with adequate fire protection and good insulation. But it seems that there's not a lot of incentive to do so on that continent.