Limited to a 1w transmitter, so it can only cover a small area. And only a few subranges within the FM band.
But no registration is required, you just need to use pre-approved equipment and anounce your contact details once an hour.
I think NZ started on FM later than many countries, so they saw the wisdom in reserving some frequencies specifically for that use. Unfortunately that wisdom was gained after the US (and most other countries) already allocated everything.
When users of of those bands were moved elsewhere (to mobile phones) they expanded to the standard 88.0mhz to 108mhz range in 2000. Looks like they reserved the 1mhz "guardband" of the expanded range for these unlicensed, low power stations.
Although at this point I think it's on a one way path to being more bandwidth for the Internet (in one form or another).
I still contend that public-access radio ought to be a thing. It can be a certified station in the same way that cable-access in the 1980's was not "pirate cable".