I think part of the problem is that Australia and New Zealand have such boring animals. Who would want to see a platypus, wombat, numbat, kiwi, tuatara, kea, or any other such creature? YAWN. No wonder your zoos are such snooze fests.
I think snowleopard's comments are off base (and a bit insulting to Aussies and Kiwis). I found Taronga Zoo and the Lone Pine Koala Sanctuary to be as interesting and high-quality as any zoo in the U.S. I'm amazed that countries with populations as relatively small as Australia and New Zealand (there are roughly twice as many people in California as in Australia and 2.5 times as many people in Los Angeles County as in New Zealand) can support so many zoos as these places do. It seems like these zoos replace their outdated exhibits at least as fast as their sisters zoos do in North America and Europe.
What snow lepard is getting at and as and Aussie I agree is that while indiviually each zoo im Australia is excellent, taken as a whole they are almost identical. Taronga and Me;bourne especially may as well be one zoo.