Large-rail U.S. cities, notably New York City, have more transit riders than the others. People using transit also tend to own fewer autos and have lower out-of-pocket commuting costs. This is a large part of the argument made in Todd Littman's Comprehensive Evaluation of Rail Transit Benefits.
Yet, most people around the world overwhelmingly prefer personal transportation. This is why autos are a big hit everywhere. This is also why transit's share of U.S. commuting in the U.S. fell from 12% in 1960 to less than 5% in 2000 -- in spite of hundreds of billions of dollars of public subsidies over these same years. (Wendell Cox has assembled the relevant evidence and made it easily accessible.)
People (unlike some researchers) understand the trade-offs. They gladly spend more cash in return for the time savings -- and all of the satisfactions of personal transport.
This is all perfectly obvious. It is when "rail investments" are presented as cost-effective that the litany bears repeating.
By all means, tax auto use for any and all external costs. This is now easy to implement. Yet, unimaginative politicians in the U.S. cannot make the leap and expect (hope) that more rail transit will "get people out of their cars."
Studies like Littman's are available to rationalize this continuing public policy failure.