It seems pretty clear based on the way that people vote, that the vast majority of Americans don't share your economic/political views & don't share your sense of the morality that relates to those views.
Really? I don't know how you can suss out what anyone is thinking based on the way people have been voting, especially in the last decade.
Do you really believe this? Most parents do want to provide for their children, some don't. The ones that don't aren't likely to be motivated whether or not the government provides services like education. The education is intended to help the children not to help the parents. Very few people want to prevent "parents from providing a little more for their kid than the kid next door", mostly they want to ensure a better opportunity for kids who don't have the advantages of wealthy, committed parents. Again, it's not about the parents, it's about the children - it's a sense of having a societal obligation to children that goes beyond simply parental obligations.
I understand that you're crying "it's for the children". I'm explaining that what you're advocating is a complete destruction of parental responsibility. Making sure that every child gets the same start in life means locking up a parent who wants to give their kid a little extra. If you want all of the kids to have an equal start it has to be illegal to hire a private tutor. It has to be wrong to confer an advantage on them.
Kids tend to emulate their parents, and learn a great deal from them. So really if you want to give all kids the same start in life, they need to be institutionalized - which is very harmful for them, but hey at least nobody gets an unfair advantage.
Children are a big motivator for parents. Parents spend gobs of money to get in to better school districts. They buy houses they don't need and burn extra time and fossil fuels to get to work so that their kids can go to a slightly better rated public school. It's a big driver in the housing market.
I get that you're looking at this only from the perspective of children, but the implications of giving everyone the same start are quite destructive. A minimum level threshold, of course, I could get behind, and have already advocated.
The reality is that kids growing up & in poor rural & urban communities are disadvantaged in terms of educational outcomes. Blaming it on "parents who don't care" doesn't change that.
The reality is that some kids will always be disadvantaged compared to other kids no matter what you think is the reason (unless we genetically engineer them and institutionalize them). And we need to accept that reality, and even embrace it as an outcome of a society that is, to any extent, driven by productivity.