What’s up with Australians (semi serious)?

I’m a tourist here in NZ, visiting from the US.

This is the 2nd time on our trip that a tour guide has warned us about Australians.

The first time was hobbiton, a shared van had picked us up with a group of Australians and the driver made a comment to us to keep some distance as they drink heavily and get little crazy (they have a bar there at the end).

The second time was today in Queenstown, also getting into a shared van, driver said unfortunately it’s a large group of Aussies with us and apologized to us in advance if they get to be too much throughout the day.

No incident to report, sounds like our guides are being cheeky but still curious what’s up with Aussies on vacation