I'm a returner at teds (i.e. this is my second year here) and i live in sydney and i got on two times, so i'm thinking distance has nothing to do with it.
How you go at uni makes a difference, pretty sure if you fail a subject you don't get let back on.
Just putting this out there- college is shit. I've been stuck with stinky asians (like international asians, not australian-asians) who don't talk to you, hide from you and never wash up/clean/empty bins etc. You get no say in who you live with and they(college) are inconsiderate when it comes to a lot of things. My fire alarm was going off for 4 hours from 6-10 this morning because they were testing them.
It has also come to my attention that college is a cash cow. If you forget your room key, they charge you 5, then 10 then 20 dollars (it doubles every time) when there is a 'duty warden' who already gets paid to do exactly that- let locked out people in. They are also very inefficient when it comes to emails/forwarding mail/everything. They didn't forward 3 months worth of mail to me over summer holidays. derp.
That being said, it's cheap ($145 p/w at self catered at teds- includes EVERYTHING except food) if something breaks you don't have to pay to fix it, don't have to worry about parking, takes 10 minutes to get to shortland side/5 minutes to get to hunter side and it's pretty social. but still... i dunno if the positives are enough to compensate for the negatives.
Also! if you live at self catered you will get harassed by the kitchen staff every time you go to a teds event that is catered because they think you don't like at teds. it's fucking rude as shit.
/rant.