> AmeriStarRail, a startup specializing in high-speed and intermodal passenger rail, pitched a partnership with Amtrak to launch the "Transcontinental Chief," a high-speed rail route that would run between Los Angeles and New York in under 72 hours.

Google Maps says it's a bit over 2,500 miles between LA and NYC. (As the crow flies, but the article's map isn't too far off.)

And 2,500 miles / 72 hours is ~35 MPH.

Not exactly "High-Speed Rail", in my book.

You forgot to factor in the 50,000 stops along the way. The essence of hurry-up and wait.