I guess they'll just have to settle for (horrors!) American workers.
By auctioning based on salary you're preferring areas with absurd costs of living - which is a) not where you necessarily need to get more people making the problem worse b) reinforcing economic inequality between areas of the country.
If there's a company needing some specialist somewhere with a saner cost of living, and they tried to find such a specialist, offering above market wages, what exactly is the benefit of not them having to pay twice or thrice the effective salary of somebody in SF/NYC?