No, the thing you are missing is that corrective lenses are a thing that exists. We're really quite good at taking someone with 20/100 vision and turning that into 20/20 or better.
Oh! Oooh! I see what you're saying. I thought you were asserting the mean _UNCORRECTED_ vision of an American Adult was 20/20. It's certainly much more plausible that the corrected vision is beyond 20/20.
I would recommend, for the sake of clarity, adding '20/20 corrected' or '20/20 rectified' to your original post. If I hear someone say, "I have 20/20 vision," my first thought is, "this person has perfect vision", not, "this person wears glasses."
I'll go back and add that clarification on my replies.
EDIT: It's too late to go back and edit my topmost comment. :(
