Of course I understand. But the historical facts take the wind out of your sails - or of the argument you're making. It's not injustice by women &/or children against men - society typically taking their part, & apparently taking it out on the men before them in family courts. It's society as a whole - which means, as we've discussed, men - voters, legislators & judges - putting laws in place that enforce paternal (& maternal) financial liability for the care & maintenance of dependent children.
From what I can see, society refuses responsibility for abandoned women & children. & even with welfare reforms in the 1980s - if a family winds up on welfare & there are dependent children present, the woman must name the father. The state will then provide family maintenance funds & services, but with the understanding that they will pursue the biological father for the sums involved.
Are men abused thereby? Possibly, & it bears looking into, if that's the case. Will society @ large support abandoned women & dependent children? Not if there are biological fathers to pursue for maintenance. Ethically, that's the breadwinner's responsibility in any event; the state merely reinforces that ethical stance. & in no scenario, society - the taxpayers - are not going to support someone else's offspring indefinitely, nor even to the children's coming of age. That's rightfully the responsibility of the parents. The state will act as maintenance in case of last resort - but the state/society is never happy about that, & will offload the responsibility to the nearest likely substitute they can find, as quickly as they can, to the letter of the law.