The majority of cases it's agreed upon by the parents. Well over half. Some studies it's around 80%.

But when men talk about court bias, they use a 96% or so ststistic that INCLUDES those preagreements as "proof" that there is bias against men.

That's not how math works.

Less than 20% of divorce cases are ones that fall before a judge to decide custody. In some of those cases, custody is not an issue, meaning that's not where the failure to come to terms is. In some, neither parent gets custody, meaning the kid(s) go live with grandparents or are old enough to be emancipated, etc.

By most estimates I've seen, only about 10 to 12% of all divorce cases with children are ones where a judge decides custody.

Those and those alone are the ones you have to look at to see if there's bias against men.

And you have to look at all the factors that will weigh into those decisions.

What is the court's policy? Did the father show up prepared to show he's ready to take on sole custody or is he clueless about what those kids need? Who was the children's primary caregiver? How involved was Dad in their daily lives when the marriage was enact? How disruptive to the lives of the children will granting custody to the father over another option be, meaning will they have to change schools and stuff like that? What's Dad willing to do or forgo to accomodate best interests of the child vs what's Mom willing to do or forego?

You might not like it, but these things matter to the stability of the child.