@MiladyRenata
I'm sorry but I can't buy into the idea of treating people differently, and giving some people extra rights, because of their chromosomes.
If you really believed that men, woman and non binary people should be entitled to equal opportunities, you wouldn't care about trans people. In fact you would see us as allies because we are breaking down the idea of a gender binary determined by one's biology.
Do you really want to live in a chromosomally determined caste system? A female supremacist might, but is that really the goal of modern feminism?
The supremacy of fatherhood, otherwise known as the patriarchy emerged around 6000 years ago. About 5800 years before the first experiments in 1842 which, eventually, led to the discovery of the sex chromosomes in 1905 by Nettie Stevens and Edmund Beecher Wilson, working independently of each other.
It is clear then that as men oppressed women for several thousand years before we knew about chromosomes, the differential treatment of male and female people must have been based on something else entirely.
That something else is the reproductive capacity of the female sex. A capacity assumed for all females from the moment of their birth. And that has material consequences for our upbringing, our rights, our needs and how we are treated.
Gender as the universal but variable phenomenon whereby societies impose sex stereotypes and sex role stereotypes on each sex, is never benign for the female of the species. In contrast to boys and men, who are never penalised for conforming to these stereotypes, women and girls can no more escape their oppression by conforming to such stereotypes as they can escape it by being non-conforming.
Because gender is irrelevant to our oppression. Because it is based on sex.
That's why sex matters.
And sex is determined not by a chromosome test, but observed at birth. Based on our bodies.
And whether we are female-bodied or male-bodied, whether at birth we are assumed to be able to bear children or not, is the deciding factor. That is how patriarchal societies categorise us into the sex hierarchy. No one needed a chromosome test for that 6000 years ago.
And the patriarchy that places women on the bottom and men at the top, persists to this day. As Maya clearly states in her OP, unequal pay on the basis of our sex continues to be an issue.
P.S. I realise this comment is already too long, and biology lessons may not be welcome, but sex chromosomes are not the endpoint of sex differentiation but the beginning. As I say above, the endpoint are male and female bodies, which is why sex is more correctly defined as the combination of chromosomes, gonads and genitalia. In unclear cases, both UK law as well as the medical profession will categorise a person as male or female based on sharing a minimum of two of these attributes with their sex class.