/shrug... the CP spends more afterwards too.
It's more expensive to run two households.
I'm certain the CP didn't spend the WHOLE amounts of rent, food, utilities, clothing, etc, out of their paycheck before the split, either.
So--do you want to split everything the CP has down the middle and that's what the NCP pays? That would be one heck of a lot more than most pay in child support now, frankly.