In the latter part of the 19th century, the North Pacific Coast Railroad was built from Sausalito to the Russian River by men with timber interests in the Russian River area who were looking for a cheap way to get their lumber to the San Francisco markets. While they may have achieved their narrow aims, the NPC was always one step ahead of bankruptcy, and was never really financially viable.
In the South Bay, otoh, the South Pacific Coast was VERY successful, probably one of (if not THE) most financially successful narrow gauge railroads outside of Colorado.
The difference between these two lines was the area they served. The NPC was built, for most of its route, through sparsely populated country along the Tomales Bay - an area with little industry and little agriculture. Tomales itself generated some dairy products, but most of the revenue came from timber and the passenger traffic in Marin County and between Marin and San Francisco.
The SPC, otoh, initially ran from Newark south to Los Gatos, and soon on to Santa Cruz, and eventually extended its northern terminus to Alameda. Travel time between San Francisco and Santa Cruz was a lot less than SP's route, and the SPC did a brisk passenger business. Additionally, it ran through San Jose, Santa Clara, and the entire Santa Clara Valley, an area booming with agricultural products and a good amount of industry. The SPC also tapped the vast logging industry of the Santa Cruz Mountains, as well as the agriculture of that region. Consequently, revenues from both passenger and freight service was high.
What's all this have to do with the topic at hand? In the last couple of decades, Santa Clara County Transit Authority has spent huge sums of money to build a light rail and to establish a bus service. There aren't a lot of riders, primarily because we are one huge urban sprawl, with industry and residences all mixed up over a vast area. For the most part, the trains and buses just plain don't go to where people want to go, and if they get close, one still ends up miles from their ultimate destination. Like the NPC, the light rail has been built through an area which ultimately can't support it, so it loses money - lots of it. Same for the buses.
Public transportation and rail networks work well in true cities like New York and San Francisco. As has been mentioned, they may also work well for intercity travel, particularly if built in a densely traveled route like the Northeast Corridor. However, unlike the other countries mentioned that have viable intercity train service, the USA is geographically HUGE, with commensurate travel times. High speed track that would allow a train to come close to (but still not match) the speed of an airplane requires high maintenance - the sheer scope of maintaining such a rail network in such a large area as the USA also doesn't bode well for extensive train travel within the USA.
All just mho for whatever it's worth.
