Why is English (New Zealand) not New Zealand English

Okay, so I have changed all my language settings so that my documents should be in New Zealand English,…which is pretty much “English” English,…or correct English seeing as it is named after them because it’s their language.

However, spell check is still telling me that every second word should be spelt with a “Z” instead of an “S” (like Organisation, Realisation, mobilisation etc etc),…and that the letter U is apparently redundant and shouldn’t be included in words like Rumour, Colour, Humour etc.

This is not English (New Zealand). It’s English (US). Please fix this.

Your OS?

Your version of LibreOffice?

As far as I can see, LibreOffice 3.5.x doesn’t support spell check for English (New Zealand) en-NZ with the bundled default dictionaries.

You may try that extension → English New Zealand dictionary/hyphenation/thesaurus 1.0 (Jul 01, 2012);
or you may use English (Australia) en-AU as text language.

My test results with LibreOffice

(bundled default dictionaries, missing spell check support en-NZ has been fixed)

Australian English is not the answer - unlike New Zealand English, in which spellings are mostly British, Australian spellings are closer to American English than to British English (including things like substituting “z” for “s” and spelling words like “labour” as “labor”). Despite the construction of the Sydney Harbour Bridge, Australia remains almost as far from New Zealand as Mexico is from Canada. For spell checking the answer in New Zealand is to use a British/UK dictionary.