One of the projects I "delivered" to the client via FTP and email just today is one that the surveyor decided to do in "plant coordinates" for some reason. Basically he spits on the ground and put a target there and say that is the start point of the world, 0-0.
The issue is this map will not align with any other map ever done. Normally we work in a State Plane system that all 50 states have their own State Plane and all work together with other maps.
So this is your new word for today. Equirectangular projection.
https://en.wikipedia.org/wiki/Equirectangular_projection
We just provide what the client wants, and we can't care less why. Even if it does make me scratch my head.