In city centres, land is more expensive than in suburban or rural areas, as land is scarce. Consequentially, housing and parking in cities cost more. However, the same is not true for using the road (such as driving). Indeed, if two people are driving into a city (in one car) to run an errand, it will usually be cheaper for one person to drive around in circles while the other runs the errand, than it is to park the car and run the errand together, even in cities with a congestion charge.
What is the origin of this discrepancy in pricing? Is it merely because we haven't implemented road pricing for technical and political reasons, or are there economic reasons that there is no pricing on roads?