But sometimes they are zero-sum. The right of women and girls to have female-only spaces, for example. If a subset of males are given the right to use such spaces, they cease to be female-only spaces. By doing so, this right is taken away from women and girls.

As another example, we can see this principle very starkly in women's and girls' sports competitions. There can only be one winner. If that winner is male, or is a team that includes males, this takes this prize away from female athletes. There are also a limited number of competition spots in most sports. Any of those taken by males denies a female athlete the opportunity to compete. This is a zero-sum game.

Regarding prisons, the expectation is that penal authorities work towards the goal of no sexual violence in prisons. Policies that demonstrably make this worse are of course going to be protested. In this case, removing the most important safeguarding measure for inmate housing: segregation by sex. The motivation is actually the safety of women prisoners. It's not an isolated case either, this was the first of many.