Cost of living is a swindle, at least when it applies internationally and cross culturally. If you want to live like a local in Jakarta (to use an extreme example), you can do so very cheaply, $180 a month for a room, eat rice for breakfast lunch and dinner. If you want to live like a San Franciscan in Jakarta, it will cost as much if not more as in San Francisco. An apartment will cost several thousand dollars a mon…
Take the minimum, over all cultures, of what would be taken as a comfortable lifestyle, and then assess the income required to maintain that lifestyle in various cities to see that, in a real sense, those cities do have different costs of living.
That said, I believe the most sensible companies will not allow their HR/payroll departments to apply a standard cost-of-living formula, simply because there are bound to be prospective employees in Jakarta whose market values are higher than those of other prospective employees who happen to live in SFO and, as an employer, I'll want to hire all those people at their respective market values.