New Zealand is rather isolated geographically, it's expensive to build infrastructure on the periphery of the network. This is true for the South Pacific islands in general.
This is a snapshot of the current undersea infrastructure in the Australia-New Zealand area: http://i.imgur.com/K1t4y.png
This is a snapshot of the current undersea infrastructure in the Australia-New Zealand area: http://i.imgur.com/K1t4y.png