This comes of as yet another "I f*ing love science" type news story.
Certainly, some countries have done much more counterproductive things than NZ and some countries would have had better capacity to respond if they listened to epidemiologists more. But for all the UK government has legitimately been criticised for being slow to respond and poor at communicating, it went into lockdown on exactly the same day as NZ. It just likely had at least two or three orders of magnitude more cases at the time.
I also suspect we'll probably find that some things that people have very strong and strident opinions about don't strongly correlate to results across regions. And that the reasons why things were so different between a lot of country or state As and country or state Bs will either be unclear or be the result of factors that couldn't really be mitigated.
It might look like an "isolated island whose countrymen aren't regularly jetting back" from the outside, but New Zealand is much more connected than that. Inbound, international students, migrant workers (mainly horticulture) and tourists are huge. Outbound, LAX is only a single flight.
The quarantine was only imposed fairly recently. Until late March IIRC, self-isolation was require because it would have been impossible to quarantine ~100k arrivals for 2 weeks.
For related reasons NZ only had six known cases by mid March when they imposed that restriction. Italy had 21k cases and 1400 deaths at that point, with a few hundred more dying every day from that point onwards.
Are you sure this isn't because NZ is one of very few countries where full elimination is a viable option?
We rely heavily on immigration. Our policy planners expect the population to grow every year because of new arrivals. That movement has other effects, like supporting house price inflation. Which itself impacts the banks' expectations and willingness to lend. And so on.
Tourism and international education are very significant industries for us. Tourism employs about 1/7 workers. Even something that appears relatively domestic, such as growing food, relies on migrant workers from the Pacific.
Isn’t Taiwan also on this path?
So I definitely agree that NZ benefited a lot by being more remote and having no land borders, but we are only doing so well because we didn’t underestimate the virus and took drastic action early.