Mike, that's true, and the growth segment of their business is selling other peoples' stuff through their webService enabled eCommerce system. Lots of small businesses are hooked into it with Amazon selling and fulfilling the deal.
But I believe you are mistaken if you think they have a physical presence in NZ.
There's absolutely no reason why they should be paying tax in NZ as they don't operate in NZ. If they sell/ship something to NZ from the USA then that business is in the USA and taxable in the USA not NZ. If, as is the case presently, there is GST payable, then it is payable by the importer not Amazon. Amazon may agree to collect this on behalf of NZ but based on what's happening in Australia I doubt it will happen.
I may very well be mistaken but the meetings my wife has with them are not via Telecomference
They may well have marketing and other non profit generating roles in NZ. I know that Google do as well. If so they'll be making a loss here as they have expenses but no revenue. So I will refine my position to: they don't have a physical sales presence in NZ.
To be taxable in NZ the likes of Amazon and Google need to make profit in NZ. Selling from a USA website and fulfillment centre to a customer in NZ is not making a profit in NZ, but they should be paying tax in the USA. If you sold a widget from your NZ business to a customer in the USA and made a profit on it, you would be taxed in NZ on that. You wouldn't expect to be getting a tax bill from the US government as well, would you?