Nah definitely PATH, I was wrong about the tunnels though, but PATH runs parallel/adjacent to North East Corridor near on the Newark line, and uses the Amtrak owned Dock Bridge. Both are reasons I commonly see cited for why PATH is FRA regulated, but I can't seem to find anything officially confirming that.

Can pay for a lot of Ubers home with the lack of NYC income tax.

Is it fully separate now? I thought I had read that it was because it shares tunnels with Amtrak so the tracks are adjacent.