It's not clear to me that it "changed things in important ways" in this case if a call alleging serious damage to the rail would've similarly triggered a pause for inspection.

It's not about the possibility, it's about probability. People are posting more fake images and videos than ever before. More is categorically different.

A phone call to railway management claiming stone fall on a track, a dead cow, a stalled car, etc will trigger a slowdown on that line, a call to the driver, and an inspection.

If that's not happening then management is playing fast and loose with legal responsibility and the risks of mass and inertia.