My guess is that the risks are too high when the grounds are rough and dangerous. They need pros to canvass that sort of terrain.
I have no idea how LE is going to search a lot of the privately owned land We have family farms that we cannot possibly search. Dangerous and huge. If something like this happened around them, we'd be hard put to help LE out in ruling out that anything of interest on that property. Heck I can't even search all of my own less than an acre personal property where I live. I have some swayles and undergrowtht that can hide a lot of things. A football, a basketball disappears in there and it has taken 20 minutes to find it when we KNOW it's in there. Some of the farmland is part swamp. We would have to tell LE that they could come search it themselves, and I would not want any amateurs on it who could hurt themselves. Hard core search pros would be needed.