The more stops you have for a train, the slower, more expensive, and less efficient it is. They like hauling for long distances without stopping.

The last miles are a huge problem in villages. Train stops and you then walk 5 miles every time? The bus needs to ride every 30 minutes to bring along 5 people that’s super expensive.

Also everyone there already has a car anyways since it’s basically required there.

Cities however can use public transport far more efficiently.

They may have been talking about economic inefficiency, if you don’t have a busy enough route to justify the initial investment.

And in the US at least, there is a LOT of land, and huge amounts of it are sparsely populated. But that still adds up to a lot of people.