[duckmysick]

It should be the job of a rail or a transportation agency (like the FAA does with aviation). They should decide which trains operators can run which trains in a public space. If some of the operators are reckless with maintenance, they would lose the license to operate.

[p_l]

And in fact that's how it's (supposed to be) done.

With the maintenance and repair shops having railway equivalent of Part 145 certification, just without type ratings IIRC.