If your suburbs are not paying for the service, the answer is simple: Revise the fee schedule for the individual customers, and when they complain, hand them a list of local government people to complain to. We had fee schedules for different routes when I was a little girl, and a 9-year-old (which I was when I was allowed to take the bus alone) could figure it out. The big problem was having enough change, but there are passes now.

City mass transit typically serves a population that can't afford cars or that may not drive. They will take the bus to work, to shop, to keep in touch with family and friends, and to patronize other service businesses too far away to walk to.

If the cost of transportation becomes too onerous for people who can't afford or aren't allowed to drive because mass transit ceases to be supported by local government, this is what happens: People can't get to work, so they lose their jobs eventually. They have trouble obtaining groceries from the less-expensive supermarkets that are typically located outside of town, and so must spend more money on groceries from the convenience store. Their contacts with friends and family become less frequent, so their social support network is strained: if you're out of the loop, it's hard for people to help you. They have trouble reaching agencies that can help them and patronizing more wholesome inexpensive entertainments (playgrounds, skating rinks and parks, swimming pools), and so their lives become less well-rounded and they may develop more health problems. They can't get to the clinics for inexpensive medical and dental care unless they live close enough to walk.

The costs of unemployment, poor health, depression, isolation and idleness are less easy to quantify than the costs of mass transit subsidies (and medicaid, and food stamps, and so forth). Those costs exist, though: lower property values, decreased consumer spending, crime, addiction, abusive families. Taking away a tool for self-improvement might make economic sense in the short run, but not in the long run, and the social costs are also worth considering.

If the rest of their community is willing to throw them away, then there's no argument for mass transit apart from the difficult issue of traffic reduction and air quality. (Tom pointed out the bus exhaust problem to me before, and he's right.) But really, it's just cruel to tell people to get a job and then make it impossible to get to the job gotten.

Regards--
Mary Anne