well math does not have ultra high scaling.
the math cohort especially 4u math is extremely smart, ie high average scale, because of asians... like i said in an ealier post asian country have a way better educational system than australia... not just in math but other subjects as well. the thing is asians' don't have english as there main language, so they are not good or rather not extremely good like they are at math and science subjects.
but the hsc science is not science... its english in disguise.
so i don't know... if you make math compulsory or english non-compulsory and change science, people might complain that too many asians are taking over australia's good jobs because they'll all get into uni easier or something. but asians still manage top marks with this rather odd hsc syllabi in all the courses... that shows how weak australia's eductional system really is.
on a side note, you know that some asian countries do the math that you call 4 unit in australia starting at around year 7 or 8 without any choice. now thats skills...