[pedantsamaritan]

49 U.S. Code § 24308 says "Amtrak has preference over freight transportation in using a rail line, junction, or crossing unless the Board orders otherwise under this subsection" [0]

In practicality, I agree with you that freight lines abuse this without consequence.

[0]: https://www.law.cornell.edu/uscode/text/49/24308

[Fezzik]

Ha, I never knew! Thank you for the citation. I have taken hundreds if train rides from Portland to Seattle, and sat waiting for freight trains to pass, or for a passenger train that was late due to freight traffic, nearly as many times.