[olliej]

That would be my thought as well. I'm originally from NZ so there's negligible private schooling, the curriculum is standardized, and obviously the country does a much better job at looking after people on lower rungs of the social ladder.

Public schools in NZ are also forbidden from what NZ calls "zoning" which I think in the US is explicit and mandatory through school districts - e.g. the exact opposite.

Despite that, public schools get some reasonable portion of their funding from the council/city/region/district/etc so a public school in a rich neighborhood generally has more funding. The next biggest source of funding is community/parent groups doing fund raising and what not - school fund raisers are common in NZ - but that again means a school in a richer area ends up having more resources.

The end result is that even in a country where there's negligible private school, schools are explicitly prohibited from restricting enrollment geographically, there's a significant difference in outcomes for rich neighborhood school vs poor.