If someone is inexperienced at something (driving in the snow), they have a larger load on their cognitive resources, making fewer resources available for things like situational awareness and problem solving. Add stress to that if they are afraid of driving in the snow, and there is a further reduction in awareness and in problem solving skills, especially for a skill that they have not mastered, such as driving in slippery conditions. They become overwhelmed by the situation and make bad decisions. All of this is over and above the lack of necessary skills for succeeding at the task (how to drive in ice and snow). It all comes together to make for a bad driving experience (or in JB's case, an amusing observational experience).