I think it's less naive, I trust they're aware of the risks, and more that passport fraud of that sort just doesn't happen on a regular enough basis to require better security. Occasionally a Member of Parliament [0] or foreign intelligence agency [1] has a go, but passport fraud is overall low.
I'm sure they also have automated tools for detecting photo manipulation.
The whole process for getting an NZ passport is an order of magnitude easier than a European passport. Here in Australia I was able complete the entire process online, and they couriered my passport to me from the Sydney consulate. I also have a passport for a European country, and last time I renewed it, I had to make an overnight trip to the consulate and spend half a day getting my passport renewed. I needed to get my photo done by an approved photographer, and they also scanned my fingerprints to store in the passport's chip (they don't store fingerprints for NZ passports).
I'm sure they also have automated tools for detecting photo manipulation.
The whole process for getting an NZ passport is an order of magnitude easier than a European passport. Here in Australia I was able complete the entire process online, and they couriered my passport to me from the Sydney consulate. I also have a passport for a European country, and last time I renewed it, I had to make an overnight trip to the consulate and spend half a day getting my passport renewed. I needed to get my photo done by an approved photographer, and they also scanned my fingerprints to store in the passport's chip (they don't store fingerprints for NZ passports).
[0] https://en.wikipedia.org/wiki/David_Garrett_(politician)
[1] https://en.wikipedia.org/wiki/New_Zealand_passport#Use_by_Is...