We should spend money creating public transit infrastructure to reduce the useof cars in urban areas. Not only is it more efficient in terms of transportation,

We should spend money creating public transit infrastructure to reduce the useof cars in urban areas. Not only is it more efficient in terms of transportation, it wastes much less energy and emits much less CO2. The fact that we haven't is a policy failure. Incidentally, why would we ever let the market decide when the market consistently throws externalities under the bus?