I think I get it.
You're at the end of a cul-de-sac.
Your cul-de-sac meets, but is blocked from, another thoroughfare (not sure if its a road with a pavement or just a footpath) at a right angle, and is fenced off from that thoroughfare.
People wanting to access your road will hop the fence and then walk up the road a bit, rather than walk all the way round and in from the actual entrance to your road.
The issue here is caused by lazy developers/planners - people will follow 'paths of desire', usually the shortest possible route from A to B.
Planners are meant to understand these and keep them in mind to prevent exactly this sort of issue, but in between the 'drawing up plans' stage and the 'making contractors actually build it' stage... shit gets tossed aside and forgotten, if it was ever there in the first place.
Look at your deeds, get your neighbour to do same.
See if you can increase fence height (probably not), or plant something your side of the fence that means hopping it is not pleasant. This is more likely as typically developments only want to manage planting/landscaping for a short time. Usually the time it takes for the development to be finished and all sold off.
Plant something that grows pretty dense and spikey, you may well need a temporary fence as it grows and you may need to shell out on well established mature plants or small ones will get trampled by the trespassers.
You probably can't use anti-vandal paint on the existing fence, however you may be able to use it on your own inner fence, should you put one up, HOWEVER... you will need to ensure it is marked down its length at regular intervals, as being treated with anti-vandal paint, or you may be liable for damage to peoples clothing/property!
It would have been better for them to put a gap in the fence right in the middle of where the two parking areas join, and create a right of way there, so pedestrians would then take that path, rather than jump a fence further up/down, however that then means selling properties that have a ROW across them which puts off buyers...