There is no "grey zone". NZ cannot simply decide not to obey the law.

It was exactly that attitude which led US DOT to issue its Warning Letter on 3 April. NZ has agreed to be bound by US law for flights operating to & from the US as a condition of its landing rights and the tenor of the Warning Letter makes it quite clear that DOT does not intend to be trifled with.

Thus, as noted in #44 , initiate the chargeback and be certain to file the DOT Complaint as NZ will find itself outside the grace period offered by DOT to carriers to come into line. Anecdotally, it seems that most carriers are doing so, thus leaving NZ as an outlier. A pity for the future if those wishing to travel to the US have to make a change to another carrier somewhere enroute!

To be clear, while the Warning Letter was issued on 3 April, the rules it describes have been in effect since 2011, and in another form since 1985. This is not new or surprising.