What you want here is that the amount spent on a person is conditionally independent [1] of characteristics that are irrelevant to that persons performance given the characteristics that are relevant to that persons performance.
Why? Just on topic that leaves out two very, very important things:
1. The process is already inherently unfairly biased towards men and it will take a nontrivial investment of resources to counter that.
2. Although it wouldn't affect an individual's performance, diversity (and other things that don't affect individual performance) can affect team performance and thus need to be considered.