Well, at Sydney, unless you're swapping within degrees that are really similar and run by the same faculty you still have to go through UAC so it isn't really easier.
E.g. I started out doing BMedSc/BE(Mech(Biomed)) but then I wanted to swap to BSc(Adv)/BE(Chem & biomolecular) but they could only swap my engg major because the science faculties usually swap the science degrees, but science didn't have permission on their system because it's run by engineering so I just changed my major.