[GravitasFailure]

A a route that serves a few hundred passengers a day is also potentially profitable for an airline while a train would likely not be unless there's existing infrastructure that can be leveraged. Also, if nobody needs that route to be served any more, just send the plane elsewhere.

Edit: I'm an idiot and missed that these are 19 seat planes. No, a train that only serves 19 people a day, one way, has a zero percent chance of being profitable, and I doubt it even makes environmental sense if you have to lay 70 miles of track to support it.

[Symbiote]

For 19 people on a 100-mile route, they may as well schedule a bus.

(For example, my parents would take a direct bus a similar distance to Heathrow or several other airports. It saves parking costs and driving while tired.)