I always assumed that there is an obligation if the neighbor demands it (so the right side of the property). If the neighbor doesn't care, then you don't have to.
So I'll join this thread: our left neighbor doesn't have any fencing on our side, so no fencing for 20 meters, and on 10 meters he has a shrub hedge. I told him twice that he should do something regarding the fencing... "yeah yeah, we'll see, no money and no time." Now he moved out, wants to sell his house, but that won't work, so he has temporary tenants – a small large family. The youngest, 3 years old, knows no pain and no boundaries and races with his scooter through gaps in the hedges through our carport onto our terrace. At least that was the case in the summer. What happens if something happens now? My car under the carport, for example? And if nothing happens: do I have to start again with the new owners about the fence? Can they then rely on customary law?
Whether the hedge or us are bothered, I won't say anything about that; the kid is cute... I also won't say anything about the fact that you don't put pressure on your neighbor, but hope that if you casually mention it over a beer, it will be fine (after all, you want to get along well).