Earlier quoted context omitted.
The price of something being higher than you'd prefer does not mean there is a market failure. Child care is not a public good and there are not obvious externalities. Excessive regulation might be a factor but that is not market failure. The fact that the unsubsidized cost of child care is higher than some parents are willing to pay may just be evidence that there are no efficiencies to be gained for those parents.…
You're computing the value of a parent's career as a single point in time salary value, and not as a integration under the curve of salary earned over time. A parent may not have the cash reserves at that single point in time to pay for childcare out of pocket, that doesn't mean that the value they get from staying employed over time does not exceed that cost. Leaving the workforce starts you over at zero. Universal…
This is less and less true the further from tech you get. An accountant can take a couple years off without having to start near entry level.