I feel like this is a major part of the equation. The employee in a tech metro area has non-remote options, and the remote only employee in a non-tech area does

I feel like this is a major part of the equation. The employee in a tech metro area has non-remote options, and the remote only employee in a non-tech area does not. The company has to compete in every market, and since the majority of employees are concentrated the high cost market gets its price while the low cost market looses out. Remote still has a host of issues to work out, mostly with time zones that make it less desirable for single geo employers.