[adrianN]

Some people think that employees should be paid somewhat proportionally to the amount of value they provide to their employer. If you accept that, then a good engineer should always get about the same amount of money, regardless of the cost of living, because they always produce a similar amount of value for the company.

[golergka]

Value is subjective: it's determined as agreement between seller and buyer. Engineer of the same ability is more valuable for an average SF company than an average Chicago company.