Two separate networks optimized for opposite goals
The United States has two essentially separate rail networks. Freight railroads (Union Pacific, BNSF, CSX, Norfolk Southern) operate roughly 140,000 miles of track optimized for heavy tonnage, long trains, and slow speeds. Passenger rail (Amtrak, commuter systems) operates on a much smaller fraction of track, often shared with freight in ways that create scheduling conflicts. The freight network dominates American rail infrastructure because freight is far more economically valuable to operate than passenger service.
Japan and Europe took a different path: they built dedicated high-speed passenger networks (Shinkansen, Eurostar, TGV, ICE) on separate alignments, allowing passenger trains to run frequently and on-schedule without conflicts with slower freight. Meanwhile, European and Japanese freight rail is far smaller because trucking captured the market when passenger rail took priority. The US decision to maintain a freight-first network means passenger service must negotiate track access with freight operators, resulting in frequent delays.
Economic viability and subsidy patterns
American freight railroads are privately profitable because they move high-value bulk commodities (coal, containers, grain) efficiently over long distances where rail's cost advantage over trucking is clear. Passenger rail is inherently less profitable because the operational cost of moving individual people is higher than the fare revenue in most markets. This is why Amtrak requires federal subsidies and why private passenger rail operators disappeared.
Conversely, European and Japanese passenger rail operates profitably in dense corridors (Tokyo-Osaka, Paris-Lyon) where frequency supports premium fares and high ridership. Freight rail in those markets is a secondary service. The US has insufficient population density and urban concentration for profitable high-speed passenger rail in most routes; the economics only work on the Boston-Washington corridor (Northeast Corridor) where Amtrak comes closest to profitability. This creates a self-reinforcing cycle where low ridership makes rail service infrequent and expensive, further reducing demand.