An inter-city system doesn't make sense considering the size of the USA, but within the densely populated North-East it should be good.
Amtrac has trains that run the north east corridor and it is one of the few profitable lines. There is another one on the west coast. Of course these are inter-city. Who knows, Amtrac could probably do a better job running these local metro trains. They could not do any worse.
NYC’s subways have gone way downhill in the last 3-4 years. My daughter teaches in the City and having students stranded on broken-down or delayed trains has gone from an occasion to the routine. The MTA is hated more than ever. She’s leaving NYC and not at all sorry about it.