But it raises another issue.
With many of those countries (particularly the United Kingdom, where so many NZ residents were born) lifting their retirement ages, what they save, NZ will have to pay out. Foreign-born new retirees will be eligible for NZ Super at 65 but there will be no immediate offsetting equivalent from their birth country.
Here's what is happening in the UK.
And this is what the US is doing.
It makes sense for NZ to broadly align itself with those countries is has social security arrangements with. This anomaly is yet another reason why John Key should have thought before pledging to hold the Super qualifying age down.
(Of course it would make more sense if people had their own individual pension plans but that's not the current debate. Raising the age of Super entitlement is.)