>"Was" being the operative word.

...and it was replaced with "whatever the judge thinks is best". For judges that were either trained under "tender years" or grew up in the environment created by it. The social inertia of tender years extends beyond it being formally ended.

But then, there's notable opposition to the very idea of not favoring mother's - Kentucky passed a law a couple of years ago requiring judges to start from a position that equal custody is best unless there's a good reason otherwise. This was heavily fought, significantly by feminist groups who described supporters as the "abusers lobby", as in their mind the only reason a man would want significant custody of his children is to use them as a means to continue abusing their mother. The law passing was considered a big win by men's rights supporters specifically because it reduced bias in family courts.