Because Joe Schmo who can't drive, was taught by his father who didn't know how to drive, who was in turn taught by his father who had no IDEA how to drive, and so on, and so on, and so on. It's a never ending cycle. However, I've been involved in a push with the NTSB to require car and rv drivers get professional training for license procurement AND renewal, every two years. People aren't very bright, and they need safety beaten into their heads as often as we can possibly get away with.