That part jumped out at me, too.
> “There were wealthier people on the upper floors,” says Dragonas, “people who had just arrived from the countryside further down and poor students in the basement. That sort of vertical stratification inside a five-story building helped Athens to avoid horizontal stratification — there weren’t really neighborhoods that were only rich or only poor.
In the US before Brown v. Board, many cities were similarly integrated along racial and economic lines. It wasn't necessarily integrated within individual apartment buildings, but Blacks and whites would live in the same neighborhoods. When Brown v. Board mandated that schools integrate, racist whites, unwilling to let their children go to the same schools as Black children, fled to the suburbs, taking with them their disproportionate share of wealth and leaving behind impoverished Black ghettoes. Any Black families with the means soon made their own escape, and the downward spiral continued.
In many states, the vast majority of school funding comes from property taxes. So schools in wealthy neighborhoods are better funded than schools in poor neighborhoods, and this guarantees homes in wealthy school districts maintain their value since everyone wants their kids in those schools.
Here in Ohio, the state Supreme Court ruled that the system of public school funding relying on property taxes is unconstitutional over a decade ago, but nothing has changed.
I agree with you that economic segregation is huge societal ill. Studies show that poor folks are vastly better off when they live in economically diverse areas.