You're presenting this very misleadingly. Kanken 2 is basically comparable to something like an SAT; it covers what people are expected to have mastered by the end of high school (reading and writing, incidentally). As such it's odd to say it "requires 12 years of schooling" as if that proved something about the language.
Kanken levels beyond 2 are a different matter; they cover words that aren't in common use, and are more akin to learning trivia for the sake of learning trivia.
