The relevant issue isn't "fairness", it's "market value". There is a lower supply of people willing to work in regions with high cost of living (for the same wage).

If I'm working remotely, I'll go to whomever pays the highest (hint: it's not the company that gives me a salary cut based on location).

If.

I am working remotely. I'm getting paid "London" rates, not "Greek village" rates.

you're right, it's not about it being fair, it's about it being the market rate for your skills in your area. If you want to live in Podunk, Nowhere, how can you expect an employer to pay you twice what anyone else in your town is willing to offer you? Especially considering that you'll be mostly telecommuting. Most companies prefer to have you working in their offices. Paying NYC rates to someone working from home, in a low wage area, makes no sense.