Probably due to road conditions during the winter season. Imagine asking someone who isn't used to driving on icy roads to drive a large van full of equipment up through the Rockies
If someone's not used to driving in snow, it'll be even worse. You should not let them drive if there's snow/ice expected in the next day; or the roads haven't been cleared yet. As someone who grew up in Minnesota, I can tell you that yes, we are better at driving in snow than people down south. However, we go in the ditch a lot anyway.