AWS to begin charging GST - but not to GST reg'd entities?!

So due the "netflix tax", AWS (Amazon Web Services) sent this out...

Effective 1 October 2016, amendments to the New Zealand Goods and Services Tax (“GST”) legislation will 
require Amazon Web Services, Inc. (“AWS”) to charge GST at 15% to New Zealand based non-GST registered 
customers.

Please read carefully below if you are a New Zealand business registered for GST:

* Before 31 October 2016 – Please enter your GST registration number on our tax settings page
 (https://console.aws.amazon.com/billing/home#/tax) for each of your AWS accounts.  This will
 avoid GST being charged on your bill from October 2016.

* If you are not able to submit your GST registration number by 31 October 2016, please do so
 at your earliest convenience. 

* You may request a refund of prior GST paid on that account through Customer Support at 
https://aws.amazon.com/support.

Doesn't this seem a bit... odd is there really a carve-out in the law so that supplies are zero rated for GST reg'd entities in this case of online services? I don't recall ever hearing about that. I mean, obviously like any other GST case a GST reg'd entity can clam back the GST paid, but to not actually have to pay it in the first place. Outside of property transactions, that's weird.

Edit: Yes, there is a carve out for this instance.