The figure in the Netherlands is about €6.7k for an elementary school pupil (until age ~12, not sure how that compares to K-12 exactly). So that's a little ove

The figure in the Netherlands is about €6.7k for an elementary school pupil (until age ~12, not sure how that compares to K-12 exactly). So that's a little over half of what the US spends, and I think it's fair to say that Dutch elementary education is at least roughly comparable to US education (maybe one is a little bit better than the other, but I'd be surprised if the US one was twice as good). I don't know about other countries, but this is one metric to give an approximation about what is "plenty", although there's the caveat that you can't compare this directly: I've heard about "school lunches" and "school nurses" in the US, and those kind of things are virtually unheard of over here.