I believe the reason why can be found in the Opal File (go straight to 1979):
https://www.wakeupkiwi.com/the-opal-file.shtml
EWNZ
Nigel Gray
New Zealand is being told the country is “broke,” that we must borrow billions just to pay interest on existing debt, and that austerity is unavoidable.
Yet at the same time, New Zealand is exporting one of the world’s most strategically important assets — gold — at a fraction of its real market value, while refusing to hold any gold reserves whatsoever.
Continue reading Ask Your Politician Why NZ Is Exporting Gold at 3% of Its Real Value While We Borrow to Pay Interest on Loans