Jup, but they are already at their test capacity so they already need to priorize who is beeing tested.

So unless you have the lab infrastructure in place already (I don't know how it is in Japan), you can't really invent it out of thin air in the midst of a crisis.

The truth is that neoliberal ideology all around the globe did its best to make hospitals and health systems "more economic" by cutting (at the time) unneeded capacities, without any real concern about the resillience of the system as a whole. This is (aside from timing and culture) where you see the main difference between nations today. This is e.g. why Spain decided the privatization of their hospitals was a grave mistake.