Where did you get that idea about New Zealand copyright? Code is copyrightable here, see e.g. [1] or [2].
And it's not about belief, but definition. Copyright and patents are human inventions defined by countries' laws (which is why different countries have different rules: different definitions). In NZ, as in many countries, "Computer software follows the rules for literary work" ([2] again).
[1] http://www.burgess.co.nz/copyright-ownership-and-software-de...