"And they lose just about the same amount of money despite having to pay for their own stations and some of their own track and infrastructure (imagine if the airlines had to buy and/or build their own airports and ATC systems, then maintain them - you think they're losing money now...)"
I'm not sure you're very clear on the substantial burden of taxes, rents, and fees borne by the airlines by the airlines and their passengers. My next trip shows total taxes of $42.23 (federal excise tax, segment fees, PFC's, security fees) on a total fare of $152.00 (yes, I got a very good deal). Not to mention that the airline pays landing fees, rent on terminal space, taxes on jet fuel, property taxes, etc. Amtrak pays no taxes at all (in fact, it continues to suck money from the U.S. Treasury), so they sure as heck ought to be paying for some of their infrastructure.
And, in many cases, the airlines do bear the costs of providing airport infrastructure. Delta's building a new terminal at BOS
, Southwest built a new terminal at ISP
, Continental built a new terminal at IAH
, Northwest built a new terminal at DTW
, American is building a new terminal at JFK
, etc. Most large airports run with no subsidy from local taxpayers; airline fees and rents cover their operating costs.
Having a "national" airline for the U.S. would be simply insane. Where would the incentive be for the airline to operate efficiently? How about motivation to provide good customer service and operate a reliable, on-time schedule? How about motivation for employees to be courteous and productive when their jobs are protected by the civil service system?