For me, the reason I was never allowed to set foot in a university was German, PE, and Norwegian literature. I was suffering from severe health issues and I didn't have the energy to do all the subjects I had no interest in. So I poured my focus into the subjects I enjoyed and/or were relevant to my future plans(biology, calc, English, physics, history). I generally nailed those subjects. But because I failed German, and almost never showed up for PE, I was denied the opportunity to follow my dream and study biology.
Part of the problem is also the very inflexible admission requirements for Norwegian universities.