It's easier to hire in Japan when you already have Sony and the optics makers (Nikon, Canon etc) with past knowledge in fabbing than in many other countries.
That said, I think TSMC had plans for factories basically anywhere they could, not laying they eggs in any single basket. The difference will probably be in process levels.
makes sense, I thought that the situation is similar in Germany (Zeiss, experience in fabbing too* ) but I guess Japan is more stable now
*afaik TSMC will open a fab in Germany, but for bigger nm's for car industry
That said, I think TSMC had plans for factories basically anywhere they could, not laying they eggs in any single basket. The difference will probably be in process levels.