[heisenzombie]

I work in a somewhat related industry and have definitely heard people talk in these terms. I think it's partly because a large percentage of the cost of this sort of manufacturing is embodied in facilities costs, which scale roughly-linearly with area. Because the facilities costs are high, manufacturing is therefore packed in at the maximum possible density, which means that the production capacity ALSO scales roughly-linearly with area.

Bear in mind that actual productive output, or how much a factory cost is quite possibly not public knowledge. But area is (just look at google maps). If you're an insider with some of these ballpark area ratios in your head, you can easily come to some conclusions.

I've likewise heard people talk about building particle accelerators in terms of cost-per-meter. In particular: ballparking the cost of a synchrotron light source as a million USD per meter.