Reality disagrees. If software development could be done in India, Ukraine or whatever your preferred third world country is it would be getting done there already.

There's a reason why developers move to one of a handful of cities to be productive.

It is already done in India and Ukraine. In Ukraine alone there are like 150k+ software developers.

If you lived in a $9/h region and had excellent development skills, why wouldn't you move to a $90/h region?

Because the $90/hr regions won’t let you.

Fair enough. Not everyone will leave their family behind, not everyone will get a visa. But the "rich shores" have a massive statistical advantage in terms of talent because they attract skilled people from abroad, with little migration in the other direction:

https://www.washingtonexaminer.com/37-percent-of-silicon-val...