The problems have been the same for a few years now. As we all know, the weather does the most damage and it has been changing the landscape forever.
Everyone else using the lanes damages them a bit, including the walkers but the powers that be are generally pro walker or are even walkers themselves.
It's not about damage, that's their excuse. It's about not wanting anyone else there with vehicles. They can't see the attraction and never will, therefore they just want to stop it.
If you believe some of the things that have been written elsewhere, then you would expect that the damage caused by 4x4s is going to lead ultimately to displacement of the plates on the earths surface and exposure of the core ultimately leading to the early demise of the planet via volcano,earthquake,total planetary destruction.
I have to admit that I would still rather drive a greenlane that isn't vehicle challenging than no greenlanes at all though. It's also about getting away from it all and looking at the scenery for me as much as it is about challenging the road conditions.