I actually cycled this route a few weeks ago, I can see why people are upset. There has been a large number of vehicles come through that have absolutely chewed up the ground, in places there are multiple pathways formed as one has become impassable.
Maintaining vehicle and cycling access, as well as marking out where the road actually is, is the best outcome in my view.


I managed to find this:
With this map: https://maps.herengaanuku.govt.nz/Viewer/?map=202d9deb4dfa4c82a13536e12c58d8fa
So it seems you’re right, a very old legacy thing, mapped roads for access to subdivided land where the road was never formed by the council or it was but they didn’t maintain it.
Yep that’s the map where my screenshot came from, I got sucked down a rabbit hole yesterday & ended up exploring all over the place.