Universities have no power over the internship process. No university guarantees internships for all students. The only students guaranteed internships are domestic students with Commonwealth funded places (regardless of the university they go to).
International students have a higher priority level than out of state domestic students in Victoria (who are guaranteed internship in the state they studied in), but there are no guarantees.
Another interesting difference is that Victoria has a merit based system where graduates compete for intern spots, whereas other states are computer matched based on preferences without any impact of academics or CVs. Queensland also has more regional intern places which aren't popular with domestic students...so you could argue you're more likely to get an intern place in Queensland as an international student than in Victoria.
I don't know any information about New Zealand.