I was once riding in a cab, ranting about how private cars should be banned in NYC, and the driver spoke up and said that no one who drives in the city wants to drive there—they do it because they have to. They do it because many neighbors within the greater metro area aren’t severed by any form of public transportation.
I'd be interested to see numbers on that (e.g. what percentage of cars are coming from which locations). There are people poorly served by transit, but Manhattan also has a lot of fairly wealthy people driving, or even being chauffeured, on routes that have perfectly usable transit that they'd just rather not use. Car ownership in NYC (45% overall) is much higher among wealthier than poorer people, and especially so…
The classicist subtext you allude to above has no place in NYC transportation policy, and will likely make inequality worse. If you want to make the rich pay their fair share, then raise income or wealth taxes. A multi-millionaire won't be fazed by a $10 congestion surcharge, they'll keep driving their Hummer directly through midtown. But the commuters from Queens or Staten Island, the senior citizens that can't easily walk down subway steps, the families car-pooling their children to different activities, and the countless businesses that need to lug equipment and supplies around the city will feel the pain.
Perversely, congestion pricing will probably benefit the rich. It will clear the streets of folks that can no longer afford to drive, making their Hummer joy ride through mid-town much more pleasurable.