My wife's hometown in China used to have two options to reach from Shanghai - high speed rail (top speed ~ 200MPH) that takes about six hours or a roughly one hour flight.

Rail travel has stops and slowdowns in more populated areas that make it a bit slower than the advertised top speeds.

That's a backwards argument. Flights in California between SF and LA will obviously travel a continuous line across California. Yes, the populated areas have light pollution, but that's because they're, y'know, populated areas. HSR itself would add nearly no light pollution outside of the existing population centers, in contrast to flights.

> but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.

This is such a misanthropic point of view.

Nobody "creates" population centers. People aren't created out of raw clay, they already exist.

If population centers are "created" it's because people already exist and want to live in a specific place, often time urban.

And if they wouldn't go to these population centers they wouldn't live in caves in the dark. They would be spread over many more places, yes, creating lower levels of light pollution but lots more of them, covering a lot more land.