Just because you like trains does not mean that it is actually a solution to everyone’s problem. For example, until proper law-enforcement starts happening on public transit, nobody in my family is allowed to take it in USA (they are allowed to do so in Singapore or Japan)
We can take the LEO's that would have patrolled highways/city streets and have them patrol on public transport, same job just slightly different environment.
Can I ask why you feel that public transit is unsafe in the US?