They do, it’s called the European Union and they have publicly-funded means of transportation through it. They can freely move through the borders of any nation in the Schengen Zone without need of a passport. You can travel through most of Europe by many different means besides automobiles.

Our country is just too stubborn and individualistic to ever elect politicians that would see through the time and money required for the types of projects needed to make the US no longer reliant on cars and trucks. On top of that, it could take decades. Say if we ever did, it would just get shut down when the next conservative blow hard convinces enough people that it isn’t worth it.

Long term projects like that just aren’t in the cards for the US any more.