Government emergency services aren't going to help at all with that process either if even one person dies in a storm and the citizens and media go to the government and are like "Hey what were you doing?" "Oh we were also organizing an effort to move all the Toyota Corollas to safety" it's not going to look good.
They're going to say all non-essential vehicles that are not emergency vehicles or directly engaged in the evacuation of people need to stay off the road.