Much more people on that extremely small area actually need to drive - because they have reduced mobility, because they are carrying a lot of stuff, goods, materials or tools... Reducing NYC to one lane would stop all life in the city. You can drive through Amsterdam too in these cases - it works because incomparably less people need to.
There's also the problem of mass transit - you can't simply have enough bus/tram lines to cover people's needs if you have so many people who need to go everywhere around the city at one place. You'd have to build an incredibly number of subway lines like Chinese cities have, which is a huge investment.
There's also the problem of mass transit - you can't simply have enough bus/tram lines to cover people's needs if you have so many people who need to go everywhere around the city at one place. You'd have to build an incredibly number of subway lines like Chinese cities have, which is a huge investment.