Looks like Air NZ are adopting the same strategy with their current Aussie sale that says "Add $75 each way for travel from any Air New Zealand serviced domestic airport." but fails to mention that the $75 add-on excludes trunk jet flights and is actually only available from regional ports.

Obviously pricing does vary on different days but it doesn't take much searching to see you can fly from any regional destination in the North Island as an example and get good availability to fly to to AKL and then SYD on a widebody for $75 more than the same fare ex AKL but that there is no availability of $75 add-ons ex WLG.

I had this very discussion with them last year and they promised to do better - their advertising did change but now it's just gone back to how it was.