James Kwak: Understanding the Budget Deficits :
"If Medicare were fully self-funding, I think this would help clarify the relationship between taxes and benefits, and people would be more willing to pay the taxes necessary to get their benefits. As I said in the Atlantic column, how much you’re willing to pay for Social Security comes down to how much insurance you need, and that’s a question you answer differently from the abstract question of how much government you need. If the same were true of Medicare, it would be obvious that as health care costs rise in general, the amount we pay for Medicare should rise at the same rate. As it is, it’s hard to explain why general tax revenues have to go up constantly because of health care inflation. On the other hand, it’s possible that making government finances more transparent will just make people want to pay taxes even less, so I could be wrong."
This applies manyfold to transportation. People thinking they pay taxes into a general fund and government produces (or doesn't) transport will be a lot less motivated or trusting then if they pay tolls, charges, or fares to a Roads or Transit organization in exchange for services. Government should be unbundled.