Australian magpies are not really related to the crow familie (which includes magpie).

And, from my experience, don't atteack random people but those that got to close to their nest. Whatever their definition of close is.

This is just crow slander, they're magpies. So corvids, but not crows. And the people are walking under their nests.

I believe crows can be more aggressive than ravens, maybe because they hang out in bigger groups rather than pairs. I haven't heard about it being limited to Australia, though.

We only have a couple of species of crow and if you're on the east coast then you're pretty much guaranteed to be seeing ravens. The crows are in the centre and the west coast, in the dry parts.