Yes can see how this happens. NZ Legal Team have had time to decide on a proper policy (they initially took this approach then changed to give refunds when people pushed back re POS and US citizenship). You can see that they've probably decided that the risk to cash flow of paying refunds according to DoT is higher than the risk of not following DoT rules. Remember that only a tiny percentage of people flying to the US or through to LHR via LAX (originating in NZ and Australia) will be aware of DoT and most of those that are will take NZ at their word it doesn't apply and accept the credit. It's a very few number of people that will know the DoT rules aren't being followed and then make a DoT complaint and/or file a disputes tribunal claim here in NZ. And I'd imagine Air NZ would probably get a slap on the wrist from DoT and they'd say "oh sorry we misinterpreted, how about no fine and we process the refunds we should have".