I guess it depends upon what you believe people are actually seeing at these locations. I've spoken elsewhere on here that while I don't necessarily believe in ghost in the 'spirit' sense I do find it fascinating that in certain geographic locations a significant number of people will sometimes experience something which they later discover that others have also experienced sometimes years, decades, even centuries apart.
Namely seeing something which gets attributed as a 'ghost' but often simply seems to be a figure performing a sequence of actions, which multiple people seem to attest to having also witnessed.
We see that in multiple accounts from Bluebell Hill, from the A15 Lincolnshire road ghost and seemingly (plausibly) this chap on horseback here.
I personally believe that while it would be impossible to quantify why all those people have seen 'a ghost' on a road my gut feeling is that rather than some kind of notion of restless spirits actually being in-play here there is plausibly something in the local geography at these sites which is causing people to see something which happened decades earlier replayed like a moment of film repeated. Like somehow an echoed moment in time has been recorded by the landscape, and under some unknown set of circumstances is occasionally replayed by means unknown.
I often wondered if the A15 road ghost wasn't in some way related to the wavelength of broadcasts from nearby RAF Cranwell, for example. That the introduction of radio signals from there might occasionally be triggering something.
The Yithian's own experience in the area above (while it didn't conjure any spectral horses or riders) was described as a "a slight hum and the car vibrated noticeably" for 6-7 minutes. It's also been speculated on other threads where Bluebell Hill has been discussed as to whether power lines or radio signals in that area could perhaps be connected to the experiences which others have had.
I don't offer up any cast iron explanations here, of course.
But I do think that their might be *something* which connects cases like these. Something currency unexplainable. It's what makes them of Fortean interest in the first place.