Unfortunately, halloween isn't really a big in Australia.
Shops try and cash in on it though, and advertise it in attempt to sell more sweets.l
I remember going trick or treating when I was 11, and had to explain what the point was to the majority of people who opened the door.
I live in a country town, so things may be different in the larger cities, I don't know.
Its a shame though, because it looks like so much fun, dressing up, then stuffing your face with all sorts of sweet goodness!!!