Some of the local illegal road repair crews are well-organized. They descend like a flash mob with heavy equipment when the odds of getting caught are near zero. The Feds are incurious about who is maintaining the roads illegally because it is kind of doing them a favor.
I first learned about this when I naively started jumping through the hoops to get permission to repair a remote road. One of the local ranchers heard about it, pulled me aside, and explained how things worked while admonishing me for ruining my plausible deniability. The whole thing was wild.