Those of us who live outside the main cities get royally screwed by Air New Zealand. We all know this even though it's difficult to document properly - complex pricing doesn't only suit mobile phone companies.
Things are different on the main routes because they have enough travellers to support competition
The boot is on the other foot for regional airports, who are keen to retain and increase airline capacity, but there are no corresponding disclosure obligations on the only nationwide carrier: Air NZ.
It is not unreasonable to suspect that AirNZ is using super-profits from regional travel to help it compete harder on competitive routes. That might be a good thing overall, but there is an obvious risk: that rivals get driven out of some routes which revert to monopolies.
The really interesting question though is what, if anything, could/should be done to promote competition on regional routes. I'm not sure of the answer, but I wonder if a carefully designed information disclosure regime might be helpful. Australians have way better public data on such things, including detailed airport-level data on plane movements and passenger counts. Copying this would be a good start, but there might also be a case for requiring the dominant carrier to disclose average fares. The benefits would be a better understanding of the scale of the problem and of where the dollars are for entrants. There would also be costs, but surely this is at least a question worth asking?