I think its that alot of people don't realise that a mark of 51 in English, is not going to get you a UAI of 51! Eg. "The Debate" in today's Telegraph (yes, i know, the telegraph, but bear with me). Brendan Nelson - Fed. Education Minister. "Many employers are sick of hiring university graduates who are struggling with basic grammer and spelling."
From that, I sort of guess that he doesn't understand the principle of the UAI being a rank, not a mark. Someone has "basic grammer and spelling" and just passes standard English is unlikely to go to university because English must be included in the calculation of your UAI and unless they got amazing marks in their other subjects... won't be at uni. I dunno, I think its just a stupid idea ... this isn't easy.