You'd be surprised. Note that Sioux Falls, the capital of South Dakota, has substantially lower average lows in Winter than Helsinki.

https://www.timeanddate.com/weather/finland/helsinki/climate https://www.timeanddate.com/weather/usa/sioux-falls/climate

Yes our car-dependent infrastructure is an issue, but it's infrastructure we've built up for the better part of a century. Changing it will be slow and gradual, and in the meantime cold weather and darkness are issues in much of the country. Also hot weather in other parts of the country (heat stroke can be a serious concern in the Southwest)