My theory is cars. Everything is spread so far apart that local businesses can't rely on foot traffic to spur interest, and a 15-minute driving radius doesn't

My theory is cars. Everything is spread so far apart that local businesses can't rely on foot traffic to spur interest, and a 15-minute driving radius doesn't include all that many people. For many people living in suburbs there's no city center to speak of, and they meet all their needs at the local strip mall full of national and multinational restaurant and grocery chains with name recognition.