Neighbors on a street in London don't love but do tolerate each other, and deal with the implications of close proximity and shared responsibilites moderately well. In the US it's much easier to move somewhere and get a parcel of land that makes you feel like a sovereign property owner. Your neighbors are not as adjacent, and may even be ignorable.
Obviously this doesn't cover the millions of Americans who live in relatively dense (generally older) cities, but it does impact the millions who live in suburban, ex-urban and rural parts of the country.