Its all about 'acting reasonably' within the law. I've had a strip for over 15 years, I used to have another strip which was PPR to anyone. There I used to fix rabbit holes and all the usual stuff. However as a condition of the lease, I also had to have 3rd party liability. The strip is in a coastal area and prone to rabbits. so everyone was briefed - stay within the marked areas - outside them and there is no guarantee.
So some character from a flying club taxis to the parking area, decides his C152 is far too heavy to push and loops around outside the marked area. On his way back to the strip he puts the nose wheel into a rabbit hole and shock loads the engine.
The group make an insurance claim, helpfully mentioning that I hold liability insurance. Their company tries to recover its costs. After a fair extensive exchange of letters, including the written insrtuctions sent to the group before they got PPR and some photos the company grudgingly decide not to go to court. Of course they did, because there was a maintenance and inspection scheme, there were markings and there were explicit instructions. In other words they had no case.
On my own strip I do not carry insurance and have no intention of doing so. People get PPR if I think the strip is in good condition and the people are up to using it (much more of a problem than the strip's condition).
There are a few very counter intutitive cases - but in most of them we get the headlines not the detail which 'justifies; them. If you hold insurance my experience is that people will try and claim, the last thing they usually want to admit to is the incompetence that damaged their aircraft. Robust defence is probably enough but the cost of the insurance is similar to that of an aircraft so it is pretty expensive.
Far better to simply act reasonably - check the strip, give clear instructions and accept no further liability.