There are a lot of tax complexities around hiring outside the company's country, so I don't think this is going to be as common as you'd like it to be. And if I were you, I would reframe the monetary compensation, rather than saying Westerners are overpaid, perhaps it's non-Westerners who are being underpaid.

I don't understand this weird thought process in the software industry where a certain contingent of developers seek to undervalue their own skills against their self interest...