This isn't Europe, and you can't necessarily repeat the same things that work in Europe and expect them to work here also.
That's not correct. Parts of the US - especially in the north-east - are very much like Europe, and both heavy rail and light rail are viable in those areas. That's also where the bulk of the population lives.
You live in a very big and diverse country. Just because something won't work in rural Arizona or Nebraska doesn't mean it won't work anywhere else.
Science is what happens when preconception meets verification.