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"You don't hitch a race horse to plow a field."
~my Grandpa (farmer out on the plains) who I'm pretty sure is older than your mom since he'd be 120 something if he were still alive.
So maybe it came from somewhere, but just not wide spread?
Side note, my grandpa would say this, and shake his head any time saw one of those over sized half van, half truck (half assed at both) monstrosities in the lot at the farm supply store