It's not because of disadvantage, rather it's because you live in their feeder area, and they want to encourage local students to go there. It's offered by lots of unis - I know of at least ANU, Newcastle and SCU.
You can get a max of 6 at UOW. You can get the 3 points for going well in your subjects related to your course and another 3 for being in the "drawing area" (pretty much for living in the Illawarra I think...?)Every uni offers bonus points except for Sydney I believe.
So happy, the course at UNSW I want to get into has a requirement of 81.65, I got 81.15. But with 5 bonus points I will get in
Wollongong offers up to 3 bonus points.
UNSW offers up to 5.
UWS offers up to 10.