The cutoffs aren't cutoffs in the same way they are for other courses - they're the minimum UAI you need for the that uni to consider you. Of course, as well as that there's the UMAT and interview process which you need to do well in as well. As I understand it, at UNSW UAI, UMAT and interview are equally weighted (but interviews are granted on a combo of estimated UAI and UMAT) whereas at Newcastle, the interview gets the most weighting, then UMAT then UAI. (and interivews are given on basis of UMAT i think). I don't know how the other states' unis work it.
The upshot of all that is that although your UAI is important, you can't forget the other parts either.