I do not believe the reasons stated in other answers. The only difference between this approach plate and other approach plates for the very same aerodrome in the same AIP like this or this (also RNAV, but RNAV GNSS, not RNP) is the type of the approach. The level of details of the map, for example, is exactly the same.
One needs special equipment and a special approval for this approach and cannot just fly it according to the map or select it in a normal Garmin.
The plate misses something important and it is NOT the details of the map. These are the actual minima to be used for the approach (I do not get what other navigation some suggest other than the approach for which the map only exists...). Notice the important notice:
Minima figures are indicative only. See CAANZ RNP-AR operator approval for specific procedure minima.
So this approach plate is not enough, more information is needed to properly perform the approach. Not to do other unspecified navigation, no-one would do that, but to fly the approach (or the associated missed approach procedure).
The AIP (ENR 1.3) also says:
1.4.2 Special RNP-AR approach and departure procedures are designed to criteria that differ from ICAO specifications and have been approved for use by CAA. These procedures are only available to operators with contractual arrangements with the procedure design organisation. Tailored instrument approach charts and navigation data-cards are only provided to contracted organisations. CAANZ approval is also required.
1.4.3 The Special RNP-AR procedure charts are annotated with the applicable restrictions. They are published for the use of ATC and for situational awareness by other aircrew and are not available to be used for navigation purposes.