Children need financial support to grow as an individual. The very first moment there's a child produced the parents are immediately billed. There's money needed for food, baby supplies, and even schooling in some cases. Some cases are unfair and give custody of the children to the spouse that shouldn't even have responsibility over the child. We're living in a fast past world that's ruled with money. This would be fair for both males and females. Feminists are constantly stating that women are independent enough to create their own money and MGTOW members are saying marriage is a trap because it's a trap for women. I believe this would be a fair way to settle the score and produce stability in marriages.
Financial income does not raise a child. If only financial income is important than any institution that has enough money to pay for material needs of an child could be a parent. Children have emotional needs that are much more important than financial needs. In the case of divorce, child should go with the parent who is more involved is child's growing up and who is psychologically more capable of raising a child.
We could say that money is everything nowadays. But for a kids, they'll say that parents love is more important. That's why a spouse with the most financial income doesn't really helps. Children want to be loved by parents, not by the money. If they go to the spouse with the most financial income, will they be happy with those money? I don't think so. Children raised up with parents love and care, not with the money.