Yeah I think they're usually a very old legacy thing, but i'm not sure if it was at the point the land was parcelled up or in later subdivisions. Or perhaps at some point someone did a map based roading plan.

There's a few to the north of the town I grew up where they were clearly planning a road with a bridge to provide additional connectivity and it just never happened. You can usually follow the paper road and it'll get a certain way along and either end across the river or stream from the other end, or sometimes turn into a driveway some distance from the other part.