> The MTA is a “public benefit corporation“ owned by the State of New York.
I've explained in a comment below what a public benefit corporation is. Court rulings have confirmed their status as private corporations, even though the governor has the authority to appoint the board of directors.
> Which are not part of the federal government and so able to make copyright claims.
If you'd like to be deliberately obtuse, go for it, but I think it's clear the original comment was in reference to the fact that state and local governments can own copyright (they can, but that's irrelevant here, because the MTA is not a branch of the state government).
I think that point is that everything is covered by copyright, by default. This is true for all entities - corporations, individuals or government. It's automatic.
The works of the federal government are a well known exception. And while I'm sure there are some state/county/city governments that also place their works in the public domain that's not the default.
It's a pretty fair generalization to say that if something wasn't produced by the federal government that it is most likely covered by copyright.
I've explained in a comment below what a public benefit corporation is. Court rulings have confirmed their status as private corporations, even though the governor has the authority to appoint the board of directors.