Most people don;t live a neat, "point a to point b and back" life. More like "home, work, food, shopping, appointments, night school, home." Also, availability doesn't always coincide with your schedule. If you need to get somewhere and noon, and the train goes there at 11:00, 12:00 & 1:00, you have to leave in time to make the early train, arrive at the destination station at 11:00, then make it to your 12:00 meeting.
The extra time wasted getting where you need to go before time to be there offsets any time you might save by not driving in traffic.
Then, just as you get on the train, it stops. an hour later, they have you on your way.
If done right, it can work. But it comes with a change in lifestyle. Depending on context, the change can be big or minor. Also depends on motivation.
When I lived in WA, a downtown Seattle group subsidized bus passes, which was a $300/month saving over parking. While I didn’t like it at first, in retrospect it did have a lot of positives. The route I took had a bus ever 5-7 mins, so it was really convenient and actually saved over driving alone due to bus express lanes. There were limitations, like the timing between busses expanded after a certain time.
Somewhat similar to Japan. Lifestyles and commerce changed around the train system. Like the food and shopping really convenient at the station. Not quite the lifestyle I’d want, but not bad and I could’ve gotten used to it. Many friends to did TDY for 3-5 years there also learned to appreciate.
But, like anything, IF done properly can work. Huge if. When rail first came up, I felt it cools work if planned properly. Once I parallels to BART and the L, knew it was trouble. Totally different contexts.