The main reason modern manufacturing is in (mostly south) China is the ecosystem! For electronics specifically, you have a tightly woven network of suppliers, factories, part distributors, logistics companies, and lots of local expertise tying it all together, as well as lots of established relationships and processes that keep it running smoothly. A factory, however highly automated, does not run in isolation. Of course you can build that kind of ecosystem elsewhere, but that's a 3-4 decade project and requires enormous investment at high political and financial risk (which is what China did in the 80s with the SEZs).