Driving a car is not that difficult. The instructor may have a few tense moments while teaching someone how to drive, but once you have a few miles under your tires, hopping in the car is not a stress-inducing event. Aside from a few people who are into off-road driving, most people never drive on anything but smooth roads with at most a few rough patches. You don’t need any special training to drive in the mountains, and weather is not much of a problem either. If it starts raining or snowing, all you have to do is slow down and be extra cautious. If conditions get too bad, you can pull off the road and stop. While most people drive every day, if you miss a few days, or even a few weeks, you have no problem the next time you drive. Most cars are so similar that you can rent a car you have never driven before, adjust the mirrors and head out without any problem other than perhaps finding the switch to put the window down at the rental-lot exit booth.
Flying an airplane is a very different experience. To be licensed as a private pilot, you must fly at least 40 hours, with at least 20 hours of dual instruction. Most people require half again as much time. Want to fly in the clouds? Tack on another 40 hours or more of instruction. Even at that point, the instrument-rated private pilot is hardly ready for all that aviation has to throw at him. Every airplane has different systems and different flight characteristics to the point that a pilot needs to fly with an instructor before operating an unfamiliar airplane for the first time. Airports vary greatly from long, wide runways to short, narrow mountain strips nestled in the trees. Taking off or landing on a gusty day is much more difficult than on a calm day, and controlling an airplane bouncing down an ILS approach in a storm, with the roar of the rain making it hard to hear the controller even with a headset on, is a whole new challenge.
