There are multiple unwritten rules among folks, or rather, accepted facts that are so obvious one doesn't need to present a justification for them. For example, everyone knows that winter isn't your ideal season for traveling, nor anyone is foolish enough to embark on a journey in such harsh weather.
Apart from the condition of the roads, the trip itself is dangerous enough to scare anyone to stay home. Overall, the risk is too heavy compared to the benefit they could gain out of it.
However, not everyone has the leisure to be picky about the time of their journey or their destination. Some are bound to cross the snowy roads, and some simply have no other choice.
