A big difference, in Australian society, is that unlike Americans hand guns had little presence. They were rarely owned by ordinary people, only by security personell or criminals. It is very hard to get a pistol licence in Aust, and if you do, the terms are such that one cannot carry it around, it has to be locked up (so why have it?)
But at the moment, hand guns are just totally flourishing on the black market. Criminals in Sydney have them, and a large number of odd people manage to get them. There was a murder a few months ago, where a pharmacist was shot dead by a 13 year old boy who had a pistol! There is also a large number of people - especially in ethnic communities such as the Lebanese - who just decide that they would like to have a hand gun. They go out and buy it illegally for cash. As many of these are working in high risk areas such a taxi driving, and petrol stations on night shift, one can't altogether blame them.
As I said, they're a different breed, apparently more docile.