Security vulnerability on U.S. trains – known for 13 years
tomshardware.com
tomshardware.com
The system with the vuln is just an overlay.
It is noted that the vulnerability hasn't supposedly ever been exploited in real life.
Apart from a targeted attack on multiple trains it does sound like this attacks likelihood is fairly low.
Perhaps if the USA were at war within another bordering nation who had physical access then it might be higher risk. But the trains are within the US with no bordering nations at much risk of doing anything on each other.
I'm not saying the people at the top aren't wrong, but we live in a world of differing priorities.