How can you call the LD routes corridors when they frequently show up multiple hours late, or even if on time, in the middle of the night? Not to mention they're often slower than driving and certainly much slower than flying.
Some people can’t or do not want to fly or drive, so a late train or middle of the night arrival is still better than not being able to go visit a sick relative, family, maybe a medical specialist.
Remember, this is a large & diverse country. There are large areas without all the convenience s that densely populated areas have.