Common Sense = 1/Education?

...Well, that's not quite accurate in this particular instance, but it's probably true in general. Anyway, I now count three people I have encountered in the course of my life who did not know The Wizard of Oz. Seriously, what? It's one thing to have never read or watched it (although I would seriously judge for that, it would be a severe case of pot and kettle, so I would have to refrain), but to have never heard of it? Whaat?