NZ is in a unique situation. Canada's high taxation throughout the 90s and 2000 created a "brain drain" (i'm part of it). The response was so great PM Harper had created a fast track immigration program to attract expat Cdns (who married abroad with children) that they can easily move back to Canada. NZ doesn't have this problem because residents & wealth can easily move to Australia (no immigration requirement). A move that a Cdn can't do by moving to the USA.

The NZ gov't may be too blind to wealth moving abroad, and looking to upscale into a high end house is not wise when the buyers of those houses have... moved abroad.