Also, if there’s a problem with a train, the whole rail goes down. If there’s a problem with an airplane, the other planes have a whole lot of sky they can still use.

That's not how rail works.

There absolutely are passing places where a train can hop onto the left track and then back again, or just a long stretch of an extra track going parallel to the main route where either the faulty train can sit and wait for repairs, or the working trains can jump around the faulty one.

Source: living in a country that actually has a working passenger railway system.

This passing problem was solved a long time ago, it's just that the freight rail corps in the US have "optimized" for trains that are longer than the passing rail sections. It's extremely bad for the entire rail industry and the cause of many of the derailments and accidents, but because capital always gets its way in the US, nothing significantly has changed to resolve the issue.

It's very frustrating how often there are perfectly workable solutions to making the world better, but if it doesn't have a fat profit margin, it just gets strangled to death by capital interests in this country.