Will a trans-state railway work in the US ?

As I read the news about SE Asia seeking to build a transnational railway eventually from China to Singapore and linking eight countries in the region, I began to ponder on the US rail system. As a developed nation/country, the rail system in the US is not well-developed. Nobody takes the train from coast to coast and along the coast from state to state, for commute or travel. It's either by car or by plane. My hoob who commutes to work via the Caltrain tells me that the train is mostly and usually empty. WHY?

Is the rail/train system so lousy (eg. frequency, comfort, connecting stations or lines etc.) that people just refuse to take it? Or are fares too expensive?

Europe has done it (Eurotunnel, Eurostar etc). SE Asian will do it. Can the US?

What do you think of the rail system in the US ?