There doesn't seem a reasonable explanation, other than it's always been that way and it's too much work to do it any differently.
There will be historical reasons - those who fought for king and country at war and iwi who have a treaty-based relationship with the crown may value the monarchy more than many others.
But for a long time now we've been an independent nation standing on our own two feet - even if God Save The Queen is still an official national anthem of New Zealand.
I'm probably one of the many who doesn't mind the monarchy, but only because the alternatives include an elected president.
Would you want a politician as our head of state?
There are some perfectly normal and reasonable MPs - Rotorua has been lucky enough to have had a string of them.
But party politics is ugly and ideally a head of state would have no such affiliations.
And who's to say a republican election won't yield a hereditary winner - born into enough money and influence to run for office and win.
If we are ever to part ways with the British throne the best option would be appointment by Parliament of a figurehead, someone a nation of New Zealanders already respects and holds in high regard.
We're not short of those.