[T]he meaning of the word "profitable" itself is subjective. We could argue that getting enough revenue to pay for a transit service is profitable if all the money comes from fares, but we could also argue that a transit service is in the black even if most of its resources come from a devoted tax base, as long as all revenue -- fares and devoted taxes -- eventually pays for the services a transit system provides. We have made a decision in our society to subsidize transit; what that actually means is that our government takes some general revenue and diverts it to transportation, rather than relying only on user fees to cover operation costs. But the rhetoric of our politicians and advocates rarely takes this truth into account.
The question of transit profitability is especially germane given the debate going on over the stimulus bill in the Senate right now. So far, senators have voted to subsidize auto sales via tax breaks, but they won't move to subsidize operating costs for transit systems that get millions of people to their jobs all around the country.