One of the features of public transit--certainly the commuter rail relatively near my house (although I still need to drive to the station)--is that it's often very empty in off-hours but if you don't run (an insufficient number of) those near-empty trains, a lot of people are going to say screw it and drive. I won't take commuter rail into the city for an evening event in part because because I really need to time the return journey--and it takes quite a bit longer.