Here's an example of one I know really well to explain what I mean a bit more, i've blacked out a couple houses to protect the owners identity a bit, though I doubt anybody would traipse around here, given the state of it.

Starting at the top you can see the green line - that's the side of the river which is also public land, but the purple line actually stops on the other bank of a very steep gully that a creek cuts through. That last short section to the north east until it ends drops at probably a 45 degree angle or more. If you tried to take a vehicle over that crest you would not stop until you were upside down under a metre of water and the only way of getting the vehicle out again would be a helicopter.

To get there you would somehow need to drive around the side of a bluff that's at least as much of an angle or more in the 2nd section that points directly at the green line. But to get to that you have to pass the third section starting on the very left hand side of the image where it goes up about 2 metres, then drops down about 5 metres over the space of about the same.

The owners have never even taken a quad bike along the entirety of that purple line I would bet, and likely not even a two wheeled dirt bike would safely do it; and all to get to a point where you can't stop and can't turn around :)

I walked it once to get to the green bit to go fishing, but it was so sketchy I spent nearly an hour finding a way to get down & then back up the other side and came away with very scratched legs from all the blackberry and brush, no trout.