Being bad at negotiation is one case. But there are others: being black, female, old... Imagine that you are a 50 year old developer applying at some software

Being bad at negotiation is one case. But there are others: being black, female, old... Imagine that you are a 50 year old developer applying at some software company. You know that you don't have a lot of opportunities (this comes up frequently on HN), so you'll underbid yourself. And a company which would be happy to hire you, and would be happy to pay you your actual value, will still accept your underbid, because they also know that you don't have many alternatives.