Focusing on Japan is a non-sequitr. This is pretty much all of Asia and half of the EU.This isn't unique to them. Japan was only mentioned because it's probably the first country to have needed to make national population crisis initiatives (as the GP wanted to suggest).

>deeply shared cultural norms that have been reinforced over centuries

Yes and Americans had this too, once upon a time. We did a good job tearing that down in the last 60 years to push consumerism instead.

It took 60 years to get there, we aren't going to fix it overnight. And that's also part of the problem. No one wants to put the time in for the effort.