I was recently in Boston talking to the Livable Streets Alliance about what they and their many local partners are doing to help speed up bus service. I happened to be in town during the two-week Silver Line Demo, a trial period during which riders can board the bus at all three doors, not just at the front.
In Europe it's common for regional rail systems to get ridership comparable to that of the subway in the central city. But in America, this is unheard of. One reason for the discrepancy is land use: American commuter rail stations are typically surrounded by parking, while in the Paris region you see a different pattern with ample development next to suburban train stations.