The fact is that location is irrelevant for some roles. If you are looking for top talent, you'll pay top talent value. If you constrain your hiring to a single location, you're simply reducing your own pool of candidates.
Today, most labor arrangements are more and more like companies. If you were to select top companies to contract for some job that doesn't really care about location, you wouldn't be choosing companies based on that. You'd choose based on how good they are.
It's the difference between trying to buy the cheapest versus buying the best. Of course if you're always looking for the cheapest, you'll always move towards overseas jobs. But if you're looking for the best, you can get the best from all over the world by offering a single solid compensation package.
It's all a transaction, isn't it? At the end of the day my labor is worth however much I can get for it.
Sure, you could squeeze even more profit by paying overseas workers less, but then you create all sorts of imbalances that can and will hurt your business in the long run.
I always joke that if you want to hire me (I am not from the US) and pay 50-60% less just because I live here, why wouldn't I work 50-60% less?
You're getting the 1% of a lower income country, for an average local developer salary. If you want the 1% of SF you'll have to pay a lot more, even if they are equivalent in the value they provide. The company still wins, and as a result you get happier employees.
You can always cheap out, but it's never without consequences.