When WW2 ended NZ politicians went to Washington and signed us up.
The British Empire was dead and the US was the new empire.
Bretton Woods was the monetary part of it and military alliance was the other.
The US had protected NZ from Japanese capture- the power and significiance of the US was undeniable after Hiroshima and Nakasaki.
Since then we have been monetarily and militarily subservient tribute state to the US just like Canada, Australia, Japan, S.Korea, the EU and UK.
NZ is part of the 5 eyes US surveillance network and gained the codes to the USSRs comms via an embassy in NZ.
NZs banking system is 80% dominated by US majority shareholder owned banks.
Those banks gain capital funding via tax havens intermediaries and channel billions back to their US owners tax free.
NZs military is highly derivative of the US and what we buy in terms of hardware is prescribed by the US.
The US military, petrodollar and US hegemony are all part of the same empire of global power projection dominance. It pasy to be aligned with that- or at least it has done until recently when US went Trumpian/Isolationist/Insane - denying climate change and siding with autocrats. Trump knows the empire is in trouble but his population are still mostly ignorant of the true challenge China now represents.
Antway, when NZ declared Nuclear Free in the 1980s the US cancelled our membership to the ANZUS military alliance and closed access to key US markets. Not allowing US nuclear powered and armed warships into our ports was explicitly punished...and still is.
There is no doubt the US uses its military and monetary hegemony to advance its own interests...and that NZ and the others are subservient tribute states.