Women do not automatically get custody!
Women DO automatically get sole custody of children in all 50 US states when the parents are not married. Men have to fight a legal battle in court if they want to be allowed to even see their children and establish any parental rights.
Most women will pass a functional test of parenting over most men. It has nothing to do with gender.
That is a very gender-biased statement. It has EVERYTHING to do with gender.
Let's say an unmarried couple has a 16 year old boy. They suddenly break up, and the mother takes the 16 year old boy with her. The 16 year old boy wants to see his father, but the mother forbids it. The mother has every legal right to do this because she retains sole custody according to the law. But what is the sole basis for her having full parental rights and the father to have absolutely no legal rights to his child? GENDER.