Even without subsidies this company would have structural competitive advantages over US PCB manufacturers. Its silly to think a US PCB manufacturer would be competitive in the same way without having something like the digikey warehouse and associated manufacturing chains right next door.
There are 1000's of corn farmers in the US, because the US has decided it was strategic and sees to it that there is always a lot of corn production capacity, even if it means buying the corn itself or artificially disposing it in some other way like making a law to use ethanol.
The point was that JLC are not strategic because they are unique. The cause & effect goes the other way. JLC are not unique because their industry was strategic.
... wait, does this also explain apparent advantages in software as well as disadvantages in hardware that the US has?