Implementing rail in the US is going to be a huge investment. Imagine all of the support business for airlines (rental cars, hotels, restaurants, stores, parking lots, sky caps, etc.) and realize that they have to be duplicated for railroads as the mechanism is so similar. (
(Yes, you can take your car with you on a train, but most railroad travelers don't).
Perhaps the answer is to run the railroads to where these support mechanisms exist (ie: airports).
The other possible answer, perhaps, is to change the mechanism for rail transportation. Instead of parking your car, buying a ticket and climbing about a vehicle....perhaps the answer is to model it similar to our highway system - Drive your car to an on-ramp and let it transport you to your destination.