[jariel]

It's supply and demand it's perfectly reasonable.

2 devs with the same abilities will have different willingness to work in a situation because of their cost base.

Essentially, one gets more because they are demanding more and that demand is based on a kind of very hard negotiating legitimacy, and the company, on the other side of the table knows that and knows they have to concede if they want the table.

I don't think the cost of living shifts are quite that much however, they are generally not a true reflection of the change in cost of living, just a minor adjustment.