There is no real reason for people to be more afraid of using the train nowadays than using the bus, in regards to the risk of exposure to CoronaVirus. Both the train and the bus can be overpacked, so if someone is afraid of using the just-renewed train, they should be just as fearful of using the bus.

The news is reporting that the train started functioning today, but instead of the normal 250,000 people that use it on a daily basis to get to work or elsewhere around the country, only about 40,000 people reserved seats for today, and so, as of now, far only 17,000 have reserved for tomorrow. They are reporting on empty platforms, the regular crowds not present, etc.

I would say that more than the fear of CoronaVirus exposure as the cause of this is possibly a number of factors:
 - the fact that it is new. The train just started. Maybe many people didn't beleieve it would happen, with another last minute delay or postponement so they wanted to see it up and running before relying on it
  - the fact that it is difficult - you have to reserve a spot. Maybe plenty felt they didn't want to have to fight about getting a seat and if they couldnt reserve they would be stuck without a reasonable alternative.
  - many people have still nor returned to work. Manye businesses shut down, many employees were laid off, many employees are still on furlough (aka chalat) even if the business did reopen (many reopened with minimal staff), or other reasons... so fewer people are traveling for work.

and probably some other reasons.