You should read the paper. That's basically what it's about. eg. car oriented neighbourhoods mean kids don't get to play as much, and that's a factor which is

You should read the paper. That's basically what it's about. eg. car oriented neighbourhoods mean kids don't get to play as much, and that's a factor which is independent of economic/social status. But also other socio-economic factors can lead to similar outcomes (eg. underfunded schools, longer work hours for parents, and the like).