New Zealand is a small island nation (isolated) in the Pacific ocean with a population of less than 5 million.
In a pandemic, they wouldn't face all of the challenges and issues that a nation on a large continent would face - especially any large nation with a high amount of travelers from around the world.
For example, Cook County, Illinois has a larger population than does New Zealand, of more than 5 million.
New York City's population is over 18 million.
Good for New Zealand, though they are a relatively small amount of people in the middle of an ocean. Their situation isn't comparable to other nations.