Assuming the question is serious: Owners of land near the US west coast.
Not near the east coast. US property is measured from a line of reference points near the east coast, so if you use the wrong foot there, your property boundaries will be less than 1mm wrong, and you and your neighbour are unlikely to notice. But near the west coast you may be building your house/fence/whatever 0.5m into your neighbour's land.
Near part of the west coast, there are fairly large effects due to plate tectonics (centimeters per year). I would think western California must have a measurement system whose position relative to points on the east coast gets adjusted periodically, with various deeds recording positions relative to ‘fixed’ points near the west coast.
No, it's about cities, and it's as old as street networks.
Suppose your neighbour has a 30×30m corner plot and you build a five-story building 50cm onto your neighbour's plot. The street isn't going to move, so you've just reduced the size of his possible six-story building by about 2%, and 2% of the value of a six-story downtown building is worth a lawsuit.
It's the result of how the US handed out land to settlers using survey to hand out square blocks largely sight unseen. However California has grants from the Spanish crown at the root of many of its property deed chains, so the mess will be different.
Not near the east coast. US property is measured from a line of reference points near the east coast, so if you use the wrong foot there, your property boundaries will be less than 1mm wrong, and you and your neighbour are unlikely to notice. But near the west coast you may be building your house/fence/whatever 0.5m into your neighbour's land.