It's no more fair than paying based on lifestyle choices; if any employee in SF is providing labor worth $200k, then an employee in Bucharest providing the same labor is also worth $200k. The fact that the SF employee has higher expenses doesn't make their labor more valuable. Sure, they are paying more to live in a more desirable location, but that no more deserves higher pay from a remote employer than an employee paying more to live in a bigger house, or to consume more expensive designer drugs outside of work hours.