That's unevenly distributed. Lots of people in London do walk or use public transport, but you still need many delivery drivers, tradespeople, etc and it doesn't make sense for them all to live outside the city. And people who don't usually drive occasionally need to use a vehicle, and then it's more stressful because you aren't used to having to know where the vehicular entrances are. It's too simplistic to just make provision for the majority and assume that it doesn't matter what the second order effects are.