Earlier quoted context omitted.
Cars destroy walkability, cyclability, ability for kids to freely play outside, enable sprawl (hence more energy consumption hence more carbon emissions). There’s no free lunch with using more surface area, which cars greatly expand people’s ability to consume.
True to a degree but cars also make parenting easier: you get bigger houses, bigger backyards, don't have lug your kids around on public transit, deal with the weather, don't need to worry about rail worker strikes, etc. All America's missing is laws that allow kids to walk to school and adding more sidewalks to enable this, but this is changing over time (see Utah's free range parenting law).
I don't think cars are responsible for bigger backyards at all. The size of the average property where I live only seems to be shrinking as the roads get more and more congested.