> Between the trade-off bad job, no time, and car/public transport, the car quickly becomes the best solution
If you beat public transport by using a car then there just isn't enough public transit or the city isn't dense enough (likely the former, due to the latter). If you live 3km from your job in London or NYC then at least during rush hour it's likely to be faster to use public transport than a car.
> Life becomes too busy to spend the extra 30 minutes commuting per day that public transport would cost.
This is again based on the premise that public transport costs time, rather than saves time or doesn't matter time wise.
People who work in really dense cities but live far outside it so they need to drive from home are already likely to not drive all the way into the city center but rather drive to the edge of the city center, park there more cheaply, and take a train the last 10% of the way. The key is that that traffic in the city center is slower than public transport, including the wait times and walking required. Within some distance from the city center of a city that is dense enough and has enough public transport, this holds true. And it's in this area that private car traffic make little sense at all. But that doesn't mean people can't have cars. Or that suburban people won't drive. You might still want to drive somewhere on the weekend. Or you might need to drive to even reach the public transport.