Starlink is actually well suited to long-haul, over-water service because their coverage and bandwidth is the same everywhere. So in the middle of the Pacific, where only planes and boats are going to use it, the service is going to be really good. Heavily populated areas, in contrast, will have poorer performance, because there is more demand for the system. To be sure, the service is still really good, but it's not efficiently distributed.
Geosynchronous satellite systems don't have the above problem, because they are by definition parked over a certain area and can focus their bandwidth. But they have the problem of high latency.
All in all, Starlink is a good choice for ANZ, even domestically, because New Zealand is pretty sparsely populated to begin with.
Ideally, an airplane wi-fi system combines the benefits of both low-earth orbit satellites like Starlink, and larger geosynchronous ones. Those systems are coming...