[fullshark]

They require preplanning, adherence to scheduling, take more time, and may not take you exactly where you want to go.

[koenigdavidmj]

Then add more trains until you don't need to look at a schedule anymore (every fifteen minutes at the absolute worst).

EDIT: Punctuation

[throwaway76543]

Adding more smaller trains without a fixed schedule over a broader area is exactly what they're doing. These smaller unscheduled trains are called "cars."

Running empty high capacity vehicles over a really large number of routes is immensely wasteful, much more wasteful than on-demand vehicles.

[dagw]

Standing for 14 minutes in the cold pissing rain is not fun. And that still doesn't solve the problem of getting to and from the train station.

[dagw]

And even that is ignoring how ridiculously expensive it would be to run trains every 15 minutes for the 6 people a day that have to get from West Bumblefuck to East Nowhereville.