> I view salary negotiations as nowhere close to a zero sum game

I think you mean "level playing field" or something. "zero sum" implies that the employer wins when the employee loses.

But I agree with you on the above. I think the dirty little secret is that most employers have very little clue about how much a particular skill set (let alone a particular dev) is worth. So they tend to use previous salary as an anchor point to make sure they're not more than 20% more crazy than the last overpaying employer.

Cost of living adjustments is likewise a hack to help pick a number out of the air. I really doubt employers think "hey, you can't raise a family on $130k in downtown DC, so we'll have higher turnover when college hires reach 5-10 years of experience".