People expect to be free to use the countryside as a playground as a right - especially post CRoW Act. They often have little or no understanding of the issues around rural land use, commercial interests or the needs and rights of other user groups. Education is lacking, even in small rural communities where children have essentially urban parents and an urban culture beamed at them 24/7.
(In a former life) I used to act for people suing for injury compensation. The Law is clear, if I allow someone to set up a camp or platform or whatever on my land I am responsible not necessarily for them whilst using it, but definitely for any child/idiot/townie who might wander onto my land and use it, or even injure themselves trying to take it down... I would have to fence off the area so that a child/idiot etc. could not get to it.
Even if I turn a blind eye to it going on without my permission OR am unaware of it, I am still responsible for anyone using it, if I should, acting as a reasonable landowner, have been aware of it and were it reasonably foreseeable that some child/numpty might have injured themselves.
In a more recent/decent life I had to go around cutting down swings, dens etc. Kids with dens almost always have fires and used to regularly set fire to woods and heaths I managed. Public would call me a killjoy and spoilsport when I was out doing it. But the same people would happily sue me/the landowner if their little darlings fell off/down/over/burnt to death...
Sadly, we do not live in the world I grew up in. We live in a world of liability, insurance and rights.
Ooooh I feel better for that rant! Best get my 20-month-old off the worktop/toaster! (again)