[With the acknowledgement that this is a tangent from the article]: I don't have hard data on hand, but in my experience, the kind of innumeracy you point to is shockingly widespread. Many people I've talked to do not know the difference between the debt and the deficit. Some people were shocked at the election results because they conflated 85% chance of winning with 85% of the votes.

Of all the math classes I've taken, Dimensional Analysis remains the one I'd most like to see forced on every highschooler. Units matter. Unlike quantities cannot be trivially compared.