It is my understanding that the gas tax (user fee) is unable to cover the costs of the highways...? Several years ago I was told that of all the money spent in the US each year on highways, only 62% came from the gas tax. The rest of the money was general fund money moved into highway funding. It would be interesting to see how people would respond to a policy that actually restricted highway spending to only what is in the HUTF. I bet we would see a gas tax increase in short order...

As previously mentioned, the air traffic control system is funded by the taxpayer and not by the airlines. Aviation also has the 'essential air service' program. There are some 114 cities that don't have enough people using the existing air service so the airline wants to stop flying there. Congress than give the specific airline a subsidy so it will fly there even though enough people don't fly in/out of that city...

If Amtrak has to make a profit, then require airlines and highways to also make a profit...!