That barrier down the middle of Rte 9 has been there for over a quarter century, long enough for it to develop visible rust spots.
Oh, well, maybe next the graph theorists will start working on the problem of finding a route through a graph when the mapmakers lied to you about some of the connectivity details.
This may be a different problem, more akin to watermarking as an approach to DRM.
In order to prove that a map was created by a particular cartographer, cartographers add little "mistakes" in random places. Then if those mistakes start to appear in map data that they didn't specifically license, they know who to sue. There are numerous problems with this approach, and what you described may be one.
The solution exists too, in the form of the Open Street Map project which aims to create a completely open database of map data.