ghaff alluded to this, but there is also a disconnect between the cost at point of use and the sunk cost when it comes to cars. If you live somewhere where there are poor transit options, you must buy a car. Once you own a car, each additional mile is cheap, considering the conveience - gas taxes be damned.

It follows that converting a car-based city to a transit one necessarily takes away resources from the people who have sunk high costs into their acquisition of a car. That population almost always objects to transit-oriented development.