"New Zealander's returning home with Covid"
Which is the big question in my mind. Do you really want to open your floodgates to an American invasion considering how poorly they've dealt with the pandemic? I'm Canadian and the majority of us here are totally opposed to opening our border for anything other than essential travel. Even then it's been abused by quite a number of American's crossing the border and then taking a Canadian holiday.
IMHO it's not worth it if you're covid-19 free because the American's haven't even flattened the curve yet, let alone got things under control. Is it really worth taking the chance? Maybe if you walled off a section of your country? But even then at this point I'd be really leery of letting them in.