All of the "electronic" authorities/visas are automatically checked at check-in. That's not to say that you might not have a rogue check-in agent ask to see one, but there should be no need, and the whole process should be completely transparent. This is the case for NZ, Australia, the US, the UK, Canada and numerous others.

Whilst obviously not NZ, as an example, I recently flew to Canada. As a US Permanent Resident I don't need a Canadian eTA, but UA's online check-in system hasn't been updated to handle that exception (which was only added last year) so I got half-way through the online check-in process in their app and it rejected me because I didn't have an eTA. Given they are only a few dollars I went over and went through the eTA process, was approved, and then immediately just back to the UA app and tried to check-in - which this time was successful. At no point did I give United any additional/different info on that second time through - they simply re-checked with the CA government systems, who approved my check-in due to the approved eTA.