It's the same reason why it hasn't happened in this side of the Tasman either. ASA and Airways NZ haven't found a way to obtain revenue from WAAS or other SBAS systems as they are basically free to air, plus as has been mentioned the big guys don't need it.
The Kiwis have APV ie LNAV/VNAV already without SBAS or WAAS:
http://www.aip.net.nz/pdf/NZAA_70.25Y.pdf
I wonder if the 2016 CASA target is only for our charts to be redone for LNAV/VNAV?