i don't doubt that racism is a component to this, but there's also the part where breaking up the monotone suburban hellscape would make it "unsafe for kids". people move to suburbs with the specific purpose of having kids, so the place is designed to be inescapable without a car but with no clear signs of confinement, just an endless continuation of the same sanitized space. then when said kids are old enough to trust they can learn to drive in the same environment and only then released from the tutorial world they're safely stuck into whenever they come "home"

but yes, also, god forbid your children have to meet minorities or poor people, and since small shops don't pay well and have the audacity to employ non-white people, the only way is to cut them out. you can pick your shit up at the gas station, if you're an adult.