FWIW - in my world, "Bandit" racing refers to jumping into a race illegally, without paying for registration. This happens in large running races like the Boston or NYC marathons, where there is usually a wait list and/or people don't want to pay the steep registration fees, so they just hop the barriers, sneak in and run the race without getting an "official" time.
That said, there are a few areas around me that CX racers and teams frequently use for practice. These are usually grassy park areas with some hills and trees, and as fall goes on a track gets worn into the grass from people riding the same routes over and over. Eventually a Strava segment pops up. It's fun and a good way to simulate some race training. No one is out there riding this in the rain so it doesn't really get torn up.
I did get yelled at by an angry old man once for "ruining the grass" in the park, which is hilarious because a.) it's grass and will grow back and b.) I am in my 40's and getting yelled at to "get off my lawn" reminded me of being a kid.