for all its pretensions to democracy and individuality ('likeable larrikinism' - self-congratulatory delusions I think) urban Australia is a terribly conformist society, in my not-so humble opinion. Most people will actually vote formally and according to the rules, and choose between Tweedledumb and Tweedledumber. If someone doesn't like any of the candidates, they can invalidate the ballot paper by making any inappropiate marking on it (eg bogus candidates, doodles etc). This invalidated vote is then called an 'informal' or 'donkey' vote (nothing to do with US Dems here!). I don't know the 'informal vote' percentages for federal elections here, but I don't personally know of anyone just checking in and walking out. I've never done it myself but will probably do it in these upcoming elections here.