But even resources per candidate isn't a good measure of fairness. Just consider the trivial illustrative possibility of a normal job board posting that every potential candidate sees. In today's world it is likely that more men would respond than women by a nontrivial factor. Everyone who responds receives equal treatment and equal devotion of resources and, in the end, significantly more men are hired than women. Now, imagine that we have the exact same scenario but somebody is hired to stand next to the job board and tell every woman who comes by "you should apply for this!" More resources are now being expended per woman than per man but the proportion of people responding might be different without being unfair to any particular person.

Granted, there are a lot of trivialities in this example, but it's pretty representative of how such programs are supposed to work.