Yeah, I do get contacted by Japanese recruiters, and their comp in my field is pretty laughable by US standards. That said, the same applies to all of Europe as well. People literally seem to be making one third of what they'd be making in the US if they were any good.
The metric that you have to consider is salary - taxes - costs of living [including health insurance] + expected future revenues [in particular pensions] Can you provide me evidence that, say, Germany, is so much worse than the USA with respect to this metric?
Cost of living is fungible. If I buy a property in an expensive city, then I have to invest a lot of my money, but I can also recoup that later if I sell the property. In boom cities the property will appreciate and create more wealth. Other costs like food and transportation provide the opportunity to be significantly frugal if you desire to be. But with the high compensation available to top workers in tech, it's possible to not be frugal and still save a large amount.