I live outside Boston just barely out where walking to the subway is infeasible (30min walk). But, it's only $2 or $7 to park at the T station and take the train in. This is a win-win for me, if I feel the desire/need to go into Boston. I don't have to worry about paying exorbitantly for a parking garage (or finding a parallel parking space and then parallel parking), and it isn't terribly inconvenient, even with a 2-year-old.