If you're buying from a freight forwarding service then you're bypassing where a retailer want's to send the goods and it's your own problem not the retailers if you're paying double tax, I wouldn't be surprised if you can claim back that tax in a lot of jurisdictions anyway. If a retailer sells into NZ legitimately then they should abide by NZ rules, the cost of retail in NZ includes the baked in prices for the Consumer Guarantees act, GST, etc. so NZ retailers are not competing on an equal playing field with overseas retailers, and NZ consumers are not as protected. When NZ retail dies, as retail is dying all over the world, then that employment is lost, and that tax revenue is lost. And it needs to be made back somehow.
If you use a freight forwarding service then that's your problem, but if you're buying legitimately from a retailer that ships and sells to NZ then they should abide by our laws and pay our taxes.
I realise that it's ironic that I'm arguing for this when I also say that eventually we will be without borders and have a gradual loss of sovereignty but I'm not necessarily saying that what I think will happen will be good for us, just inevitable. And, we have to make the current system work somehow, and keep up that tax revenue because when retail fails we're going to have a lot of unemployed people.
Retail won't fail, though there maybe more empty shops in your CBDs. It will evolve. You can't get a haircut online, or get served your coffee through a computer screen. 140 years ago there would have been a blacksmiths aplenty in downtown Wellington. They all disappeared, and someone else took over their 'shop front'.
Just can't see how you can make sure an overseas retailer selling worldwide (incl NZ), abide by NZ consumer law. There will simply be millions of overseas retailers selling stuff online.
It isn't the job of NZ Govt/govt agency to police them, and again how do you enforce a jeweler in Tallin, Estonia to manufacture, sell or whatever to NZ standards?
Simply caveat emptor, ie as a buyer take responsibility for your decisions.