What if that's both? What if it's neither? What if is the higher earner that sacrificed an even higher position - do you make the lower earner pay them?
Then the court doesn't need to show a particular bias towards either party on this subject. As you have very astutely pointed out, there exist other circumstances which may compel a court to apply a bias one way or another. That's what courts are for.
> What if is the higher earner that sacrificed an even higher position - do you make the lower earner pay them?
If a decade of childcare materially and demonstrably damaged their future career, they should take that into account. If not, no.
Please pay attention to the words I'm using - 'bias'. This means putting some weight on the scales, not dropping a bag of bricks on one of them.
Please think about what you are saying for a minute.
You are saying that if one of the parents sacrifices their future to care for the child, and the other does not, during a divorce, the latter does not owe the former anything.
The better question is - why do you want to moat the latter parent moated from the duty of parenting so much?
Or, if parenting is too complicated, here's a simple example.
Bill marries Jill. Bill works, buys their food, pays their rent, pays their bills, does the housework, and pays Jill's way through medical school. Bill and Jill have no assets, because all the money went into Jill's education.
Jill graduates, becomes a doctor, starts making mountains of money, meets a pretty intern, and divorces Bill.
Does Jill owe Bill anything?
It's the same situation as with childcare. Bill put more into maintaining the marriage/child than Jill did. Jill benefited/was harmed less during the marriage. Bill deserves compensation after the fact.
Had the fruits of his labours gone into a savings account, he'd receive at least half of it on divorce. Instead, they went into developing Jill's earnings potential - so he's entitled to a share of it. Likewise, if instead of paying with money, he paid with childcare that was damaging to his career.
That actually depends. Some states put a large weighting on lifestyle costs. So even if Jill is making tons of money, she probably won't be required to pay anything if she has been spending it on a BMW and other expensive things. Even if that were not the case, most states would not require alimony if Bill is still working. Also, some states would consider the education costs a gift and it would not entitle Bill to anything.
> Also, some states would consider the education costs a gift and it would not entitle Bill to anything.
Would they consider rent, food, utilities, and everything else a gift too?
A marriage is a not a quid-pro-quo financial transaction. It is an entanglement of two people's lives. The purpose of divorce court is to unentangle those lives in a fair and equitable manner.
One person supporting the household, while the other mooches off them, and then divorcing right when they start becoming responsible for supporting the household is not a clean break with zero financial entanglements.
Imagine if instead of pouring money into an education, Bill was supporting Jill as she was building a startup. He kept the family afloat, he poured money into it, while it was running at a loss - and then, right as it turns profitable, she leaves him with nothing.
Would that be fair and equitable? If not, why is a high-earning education any different? [1]
[1] The difference is obviously, that in this case, the startup's ownership would be split between the two spouses, with the spouse that financially supported the founder receiving a portion of it - probably not a 50/50 portion, but some portion nevertheless. An education's ownership can't be split... But the wages derived from an education can be.
This assumes that everyone caring for children is automatically "sacrificing their career". That is not true. There are still women who are not really interested in persuing a career they'd need to sacrifice to care for a child. So simply observing the "career status" of both parties is definitely not enough for a fair ruling.
There are other factors involved too.