It is both - corrupt politicians and a large and vocal public opposition. My estimate form various public hearings in Baltimore is that perhaps 40-50% want efficient public transit, about 30% opposes it because it takes parking space and brings the undesirable element s to their neighborhood. In the suburbs, the latter is probably 60-70%.
One of the most frequently cited reasons for that opposition is "crime" - as if the city residents 9code word for Balcks) were only waiting for the bus or light rail to go to the burbs, steal that TV, take it back to the stop and wait for another bus or train to come. If that is not ultimately stupid, I do not know what is.
Of course, car lobbies, construction businesses and corrupt politicians hear only those who oppose public transit.
Wojtek