Telstra sucks. You'll get no arguement from me there. But there are a few providers of DSL out there (mostly telcos). Dingoblue is soon going to offer ADSL, the recently failed onetel also offered ADSL (as well as some other flavour of DSL if I remember correctly). Primus is also offering ADSL. (see http://www.ausforum.com/ for a more DSL info & a much bigger list)
So why does the DSL status in Australia suck so much? Because of these unacceptable "Acceptable Use Policy"s. Most providers cost ~$100/month, with downloads limited to 500MB in some cases, and extra downloads at about 20c/MB.
A while ago, the ACCC were going to look into broadband pricing, but I don't remember what happened there. The ACCC are very busy people (the same people who are going to look into DVD zoning in Australia).
A big problem is the cost of international bandwidth. Australia, the island continent really gets screwed here. Those big fat pipes to the US/Asia cost a lot, and most ISP rely on Telsta, Optus or a few of the smaller carriers for their connection. Greedy telcos, and lack of competition is a bad recipe. There was talk a while ago about the other end of the pipe (ie: US) to pay half... but this hasn't really happened (why would you?).
The ACCC is really the only hope here. There are enough people who don't care about the AUP to give Telstra plenty of income from DSL. If you don't like it, Telstra probably don't want you as a customer anyway.
So untill it costs less to put a pipe to the US, or the ACCC have another good look at telsta, we're doomed with expensive internet. (forever)