One reason is that, once you arrive, options for public transport within the destination city in the US are limited. So you need a car once you get to your destination anyhow. What do you do when you step off the train in Atlanta or Savannah?
I just spent 7 weeks traveling around Europe by train. I would not have considered that approach without the extensive local public transportation systems. Atlanta is not remotely in the same league as Berlin in terms of public transit.
I’ve never been to the state of Georgia, but I was under the impression that both Atlanta and Savannah had pretty good public transit systems. Atlanta has a metro system (MARTA) which is the eight largest in the USA by ridership. And Savannah has an extensive bus network, and a walkable downtown area where transit is actually free to ride.
I just spent 7 weeks traveling around Europe by train. I would not have considered that approach without the extensive local public transportation systems. Atlanta is not remotely in the same league as Berlin in terms of public transit.