As an American who worked in Australia, I can vouch that you guys (luckily) don't share our same crazy work ethic. I was practically alone in the office of a large corporation once the clock struck 4pm on a Friday. I think you'd fit in well in New York though because they have the same teasing sense of humor that I found everywhere down under.
As an Australian in California, and having lived and worked in two European countries too, I'd say that Australians work less hours but actually are more focused when they do work. I see a lot Americans at work, but not doing work. Long lunches, chatting to colleagues around the office, browsing websites etc. seems to be far more prevalent in American workspaces.
Interestingly, I once read a study that said that Aussies do the most overtime of any western nation, which seemed off. Shrug