Well american universities are strange.
They'd look at your UAI and raw scores but might not really understand what they mean. They'd look for SAT scores (if you've taken them) and your high school grades from year 9 onwards as well as recommendations, an essay you have to write for them as well as the application stuff you have to fill out for them...
They wanna know more about you than just academics.
I just filled out a couple applications during the holidays actually...by the way you can and should apply before you finish yr.12 cause thats how they do it over there.
Year 12 in America is an absolute bludge. you know what uni your gunna go to by the time your half-way through the year
...you can't even explain to them how much work the HSC is.
On the note, how would you try to explain the HSC to someone who has no idea what it is.
(I don't know about how any other countries work)