Actually all other forms of transportation besides trains get large subsidies.
I think you forgot about a relativley large albatross...
Can you say "AMTRAK"? Tons and tons of Gov't money poured into it every year.
That "Tons and tons of Gov't money" actual wasn't that much compared the amount used to subsidize other forms of transportation. Also, before making believe that the trains are inherently less profitable than airlines, remember that railroads have to buy or lease and maintain their routes out of their accounts and on their very public books.
Airlines are provided radar and air traffic control by the federal government. States and municipalities buy the land for and build the airports. None of these cost show on airline books.
Truckers get it good also. Interstates are financed by tax money. Truckers pay a fuel tax but it is not even a drop in the bucket of actual costs. The highways are provided essentially gratis by taxpayers. But it doesn't show up on the news so everyone makes believe airlines and truckers are 'standing on their own two feet' while railroads are 'deadbeats on welfare'.
If all the transportation modalities had to cover their own costs trains would win easily because in terms of building, maintenance, energy and management costs they are by far the most efficient.
On the other end, if railroads were subsidized by the government, if the government just build and maintained the rails like they do highways and airways, the railroads would be much more profitable than either trucking or airlines.
Bottom line is that railroads only look like "a relatively large albatross" because they compete with transportation modalities that are much more highly subsidized than they are.
If railroads were subsidized at similar levels to trucking, airlines and shipping cargo and passengers would shift to railroads and, over time, the total amount of subsidies could be decrease. The cost of travel and shipping and need for foreign oil would also be reduced.