it’s trans people who benefit
Only the male ones. The right to access all female areas is a male benefit, not a trans benefit.
Does that benefit justify the cost to female people?
Why are the male people in this situation more valuable and important than the female ones? Do you see how this has just become sex discrimination and quite frankly male supremacism that it is even being considered debatable that some females to lose all access to any resources, facilities and services in order that males can have total freedom of choice from all the resources, facilities and services?
What do we do with the females now unable to access women's resources, services and facilities? How can those women's facilities etc be called 'inclusive' when the job of a women's facility/service is to be accessible to all women and all protected characteristics? (There's nine. Not one. No matter what Stonewall says.)
Can those male people's needs be met in other ways than stripping all female resources away from female people with the heavy cost to female equality, access, inclusion, dignity, safety and autonomy, and the basic human right to not be used as a support animal regardless of consent?
Let's look at some real live current cases:
the MNetter for example who is currently trying to deal with having no access to her local rape crisis service, LA funded, because while transwomen have no less than three different groups to choose from for help with their rape (mens, LGBT+ and women's which is a mixed sex group) females get one option: it's mixed sex. The service absolutely refuses to provide a female only group, even in another building. This is inexcusable dog in the manger selfishness and intolerance. This political position would see female rape victims without support than permit them service where they can be in a female only group. Saying 'no' to male people and 'female people have rights and needs and lived experience too' is 'hate'. 
What about the MNetter who was homeless in a tent with injuries for months because her trauma prevented her accessing a women's shelter because they were all mixed sex, and her trying to explain that her needs meant she could not enter such a space involved her being lectured on how the male people came first, their trauma and needs mattered, and if she did not service their need she got nothing.
Are we in bloody Gilead or what?
It is not women who have destroyed all the good will here by providing endless experience of the realities of this political agenda.