In general, this is actually done: there are defect detectors that are installed along tracks that monitor for several conditions as trains pass over/through them. Once the train has passed, a voice radio message is sent to the train crew.

Here's an example of one working: https://www.youtube.com/watch?v=R7BGg82uQ1U

I'm not sure whether similar equipment was a factor in the East Palestine incident.

It is very odd to me that states do this very thing for trucking, but apparently do not do it for rail.

They did. It was ignored. IIRC, the exact wording from dispatch was "If it's still alerting at the next sensor it's a problem."

I'm astonished that they treat those alarms like I treated the check-engine light as a poor kid who reasoned that the car seems to still be running fine.

Thanks for the clarification.

Here's a page on several of the automatic checks that exist for railways: https://en.wikipedia.org/wiki/Defect_detector