Perhaps the quintessential pro-social activity is having children and trying to raise them well – that's where the society in 'pro-social' comes from, after all. If anything should have a government-run incentive system, it makes sense that this would be on the list for consideration. Certainly, many countries (including the US) have tax policy that reduces the burden for families raising kids, and some countries also have public insurance or mandate employers allow new parents to take time off. But I've been hearing more about government child care, and I have a specific and important concern about it, as a general policy.
It might be, legitimately, the last step in atomizing social life and destroying local communities, and not done out of necessity – obviously, people are surviving now – but as a government handout, a way for people to spend tax dollars and seem generous (I was raised to think it wasn't generous unless it cost me something, but whatever, I admit politicians get credit for spending other people's money, I might as well acknowledge that public response). And it would be a big help to a lot of families... but the social cost is probably larger than the (substantial) dollar cost.
I've been hearing the reason public schools don't teach anything is that they're secretly public child care for years. This seems a bit unfair to teachers who want to educate their students, but I understand the analysis. And I'm on the record as describing "hold humans in a room so that linear time progresses" as being a waste of human potential far in excess of the strict maintenance burden. Expanding that system, and attempting to make it as literal a "hold a human in a box" as possible seems like a moral and social disaster to me.
Governments, of course, can't take strong positions about how children should be raised. It would be deeply problematic to a free and pluralistic society, obviously, but it'd also get parents yelling at PTA meetings – a more immediate and obvious cost I'm sure they'd attempt to avoid. But people ought to have strong opinions on how to raise their children! It's an important task that takes years, and it's crucial to a pluralistic society that we try many different systems and values. If everyone's kids are raised the same, we factually will not have the diversity that makes America such a special place. We want thousands, maybe millions of different ideas at work, but with government run childcare it's possible we will be closer to just one (that one option will surely be utter milquetoast garbage, but I suppose that's a separate problem).
Of course, I'd be way more optimistic about a voucher system, but planning it as an extension of the school system means it's unlikely to happen that way.