It might be one one writer has called "sonic errors" a case of having heard an expression, and not quite understanding it, but using it... similar to mondegreens... like hares breathe (not hairs breadth), If you don't know the the words or expression.. a firm recommendation --might be misconstrued as a hard-- and then Hardily seems to make sense..

I sometime feel at the cusp-- i am very bright-- but not well educatated-- but somewhat well read.. but if i were less well read-- or less educated. or less bright.. and passed throught the "education mill"..

Jay Leno, the comedian, has a weekly special.. "Jaywalking" where he goes out and asks "simple questions"-- and see the kind of answers he gets-- recently, with the US release of "Pearl Harbor" he asked questions like-
"When was Pearl Harbor bombed?" , "Who bombed it?" "Who was the war between?", "When was the beginning of WWII?"-- the anwsers included 1924, 1967, the Hawaiins (bombed it) we were at war with the chinese.

Obviously, right answers don't get on the show... but the there is no shortage of people providing wrong answers.. and they don't all seem to be faking... I like to think its not just the average american who is this uneducated!