Many of these systems built are inefficient to the max and great public works boondoggles.
The Green eyewash sometimes blinds us to using only real practical conservation.
Many cities rely excessively on pollution belching buses that only hog space on the already congested roadways. Bogged down in traffic, they are far less fuel efficient and more labor/maintenance intensive than bus proponents claim. Granted, they are the cheapest way to go upfront, and they do add flexibility to the transportation infrastruction. But higher volume traffic corridors will always be served more effectively by more permanent rail systems travelling on their own, unimpeded right-of-way.