You are right. It is a travesty. However, a frighteningly significant, most likely the majority, of people in the United States equate your worth with your economic success in capitalist society....like you are your score in some shitty video game.
Better than that; by transferring a bit of money from taxpayers you can account for wages from 2 paid jobs, the mother's and the carer's.
There is a sort of neoliberal logic to it of course; in early childcare in my country, ratios are 4:1 - there is an "efficiency gain" if the mother earns more than childcare fees for the children under care.
But of course childcare availability is certainly not a bad thing even if there might be agendas in play.
To generate future GDP (and thus tax revenue).
AKA providing a service or product to the society. They must be useful to their friends and family, of course - but they're sure as hell useless to another anonymous person.