I believe a lot of these issues are with surveyors and some are people just don't care. People are being sold land and being told where their lines are, when if fact they are not.
When they built the housing project behind our property 30 years ago the realty company told them the 20' wide permanent easement road running the full length was actually theirs, but it was not reflected in the surveyors plot in the deed book. A few people started to fence across the easement and they were told it is not their land. It is the realty companies land that was by deeded a permanent easement as long as it was regularly traveled. (It is travelled across daily.) Everyone on both sides of the easement know they don't own the land but still some use to dump trash/branches and some have put up fences along the back of their properties extending 2' into the easement, reducing it to 18' in some areas. Trying to get along, nobody has said anything.
A old farmer in NC was putting up part of his land for sale. He create two adjacent 40 acre lots. The surveyor came out and marked them out but miss-labeled the parcels. So for 6 years my brother was working one lot and another family was working the other parcel. Then the family decided to sale the land and a new surveyor came out and marked and did a title searched and found they were trying to sale the land belong to my brother and the land my brother was on was owned by the other family. It could have gotten ugly but both had level heads and just did the paperwork to correct the land ownership issue.
The second issue my brother had was his 6500 sf house on lake gaston they bought. The surveyor showed the property line 20' from the side of the house when they went to put a MIL apartment and ramp leaving 5' to the property line. When the Doctor next door went to put his house up for sale a new surveyor found the property line had actually only been only 4' from the house and the MIL addition was 9' onto the Doctors property. In this case also level heads prevailed and the Doctor just sold the strip of land to my brother, before putting the house up for final sale.
So there are still some decent level head people out there.