When Brightline first launched its train service in Florida five years ago, it was a turning point for passenger rail in the U.S. The sleek new trains were fast and equipped with features like free wi-fi; the spotless new train stations looked more like modern hotel lobbies than the aging depots used at many Amtrak stops. It was the first privately-owned intercity rail in the U.S. in decades, and boosters argued that it was proof that private co…