Why do people from NZ get bent out of shape if you insinuate they're from Australia?

It is because they have developed an inferiority complex to Australians. Let's face it --- they all want to come to Oz & work (plus bludge on our welfare system). They must know & realize Australia (& Australians) are better than New Zealand .... otherwise the country wouldn't be riddled with them as it is now.

They become aggressive to counter their inadequacies!

Because they are proud of their heritage and are proud of their individuality. and for some reason australians and new zealanders have this ongoing rivalry, even my own dad who is from new zealand and lives here in aus gets annoyed when hes called an aussie. (Australia is sooo much better than NZ, just so you all no lol)

Because NZ seems to have this fierce rivalry towards Australia. Kinda like small man syndrome. Im an Aussie, and wouldnt give 2 hoots if someone thought I was a Kiwi.

For the same reason Kiwis don't like being called South Africans. If you can't pick where someone's accent is from, don't assume. Ask them. People would much rather you politely ask where they are from, rather than assuming they are from other part of the world.

Unfortunately for New Zealand, a lot of foreigners show their complete ignorance, and presume that New Zealand is part of Australia. I knew a girl that thought phoning New Zealand was a local call. Wondered why I went ballistic when I got this HUGE international phone bill.

So be polite and ask. Don't assume.

The same reason we, as Australians, get upset when some idiots think we're from Austria.

Also Canadians don't like being called Americans and vice versa.

The Scots, the Welsh and the Irish don't like being called English.

It's a matter of national pride and identity.

Its like trying to call a canadian american

Because we're not Australians so don't try calling us Aussies or you'll be yelled at

I have not noticed it but I would imagine that they are proud of their heritage & amazed at the stupidity of those who can't tell the difference.

because it would be like saying your from canada if your from n. america