"Difficult, stressful, confusing, complicated, complex, frustrating!" When I did my ATPL theory final brush-up lasting a fortnight at a superb ground school (well worth the money), similar observations were made to one of the lecturers who was an ex RAF pilot. When asked why, his reply went something like this "Almost anyone can be taught to fly, given enough time and money. But civil aviation doesn't want or need almost anyone and therefore a challenging intellectual barrier is put in place to keep the riff-raff out."