Next to a train line you'll need a lot of more fine-grained transport though - like buses - to get people from train stations to their final destination. In addition it needs to be as expensive (or cheap) as driving, and not take any more time.

I used to live somewhere / have a commute where the time difference between public transit and driving was negligible. Nowadays I live somewhere much nicer, but I drive to work; the drive is 15-20 minutes, public transit would take me an hour. There is some traffic issues from time to time, but even with traffic it's faster than public transit.