New Zealand does have the advantage of an ocean border and thus near total control on entries and exits.

Compared to the very porous land borders of the US.

Come on, they're not that porous, certainly under a Trump administration. People fly into NZ too.

This argument is so flawed in many ways, economies are built by people for people. Extrapolate the numbers, let's say in the COVID Pandemic a country, take USA as example, has 10% percentage of their population killed by it, would that be better to the economy?

There's multiple ways to look at the economy, the raw exchange of dollar currency in a debt chase (shit I need to run faster & pay down this stuff!), there's the productivity of industrial output (shit we need to sell more junk and useless crap!), and there's the stock and productivity in optimal life cycles (Damn, that Nokia is a tank!)

If 10% of the population went away, it would affect 1 & 2, but in any true practical lens, there's a ton of cheap empty houses, while on the other hand building repairable stuff that lasts or enough cheaply is where economies move to more complex technologies by saving time and effort in useless endeavour of debt chases or consumption-oriented wasteful productivity

Economies are built by rich people for rich people. A few million poor people dead doesn't really make a dent in them.