A big problem is now fixing our land use, zoning, and density to be serviceable by transit. Most developments since the rise of suburbia have been extremely car centric and low density which can be hurdles in creating effevtive transit networks.

People are also going to have to accept that building transit will require taking some priority away from cars in some areas (reduced parking, reduced lanes, lower speeds) and this is generally viewed as bad because people already hate being in their cars in existing traffic.