I think Vghikers has summed the responsibility for marking correctly. I remember chatting to a farmer in mid Wales a few years ago, it was fairly remote and as the way was not very well marked I asked if I was on the right track. He told me the council had sent him a pack of waymark discs a year or so previous and that they were probably still in the drawer in the kitchen, though the wife might have sent them to the church fete to sell as coasters. He was a friendly fellow and didn't seem to be too concerned where I walked.
Now in south Cheshire a few days ago, I found the stump of a fingerpost clearly chopped off by a disc hedge cutter, this was just one of a number of clues that suggest those, who do the contract work for landowners, think they are following the local attitude to public access by inflicting damage the infrastructure. On the other hand a few weeks ago walking within an estate that clearly do not value walkers and rather they were not there, the crop ways were meticulously left clear.This I think is a sign that the management of that land was mostly contracted out and the contractor does his homework properly, in planning his cropwork.
I think there is a lot to be learnt about how messages get through to the various interests that occupy, administer and work in the countryside. I have tried to ask if the difference between farmer and landowner is relevant to us users, a lot can be learnt about an area about how the occupiers respect those who visit their localities.