Your brother manages to study full time at university and earn enough to pay for rent/mortgage, bills, health care, petrol, car rego, groceries, etc? Clearly your brother isn't dedicating sufficient time to his studies.
Sorry to jump on this before I've read the rest of the thread but this is super unfair - I'm not for a second saying that you should be able to do this, but just because others can doesn't mean they aren't dedicating 'sufficient' time to their studies.
My husband is currently doing his honours (full time). He got an HD average for his pass degree (which he did full time), while working full time, paying ALL our rent, bills, food, travel costs etc. because I don't work (either then or currently - as I am a full time research student). While I get that we probably don't live the life that you want to live I think the 82% average across ALL his subjects, for his WHOLE degree says something about the amount of time that he dedicates to school.
ETA - MORE GENERALLY: I agree wholeheartedly that students should be given more than people on the dole. I think it works in two ways: it encourages people to upskill and it rewards people who want to better their education. HOWEVER, I would rather see (I think) studies that currently do not qualify for anything (such as research Master's and Doctoral programs) get something than every undergraduate and secondary school student get more than they already get. Of course - I am only talking about people who actually are eligible to receive benefits.
I personally believe that they also need to have another look at the independent status and how it can be met. Having said all of that, I can understand why parental income counts towards assessment if a student is still living at home. It's not always fair, but that's what it is.
I did get some support when I was doing my undergraduate degree, although I also worked and often earned enough that I would get very little or nothing from Centerlink each fortnight. Once I started my Master's program I wasn't eligible for anything because my program of study was not 'necessary' (even though it is for my chosen career). But, I'm not complaining - I'm thankful that I got some help and that I lived in a country in which I could access something (without having to pay it back... like many, many other [first world] countries.)