Scales hopelessly - Sometimes...
Our maths teachers (who mark hsc) have told us over and over that general maths will scale hopelessly if we cannot get into the top percentile of the state. If you get 70 in general maths, then yes, scaling will be quite bad. However if you can get above 90, then scaling will not even affect you, and if you get 95+, then you scale UP.
Big big misconception about general maths.
And also, if you get 100, then you get 100 - no scaling whatsoever.
And btw, maths is often a prerequisite, and in qld unis, general maths counts as assumed knowledge when maths is needed. Have you ever heard of a course that requires economics as a pre-requisite.