Before I start this question pertains to situations where child support is involved, paid or not.

Now when people think about kids, society considers man's wallet to a woman's body. Men have to support children financially for 18 years whether they want the child or not.

Casting that aside, why is it that the money that men provide only counts? Scratch that, why don't people think about the money of the primary parent? Primary parents don't just spend every dime they own on themselves while the child support pays for everything else. Bills where the child lives, food, health care, school activities, clothes, etc. are also paid by the primary parent in addition to child support.

So where did this attitude, first originate from anyway?