Can you check the links in the OP? I don't see anything about New Zealand in the link you posted, and the link is an article about the US boarder protection agents searching phones/laptops when they enter the US. Nor do I see anything about any kind of fine for not complying.
Here's the article I saw about it:
Business InsiderAccording to the article, officials need "reasonable cause" (which I presume to be similar to
probable cause) that you have broken a law in order to demand your phone password. This is very different from being able to demand a password simply because you are crossing the boarder.
The law only applies to physical devices and not to cloud passwords. The law nevertheless is not something I support.
I suggest to have a "fresh" device if you plan on entering New Zealand, and have your information stored in the cloud in a way that you can access it once you are past the border.