To respond to the original Topic Starter…
This is from my personal knowledge of what I know that has occurred in the Argentine road privatization case.
Just like with the start-ups of the railroads in the U.S., initially going small distances cost a lot of money, while going larger distances cost appeciably less. Particularly because the farther out you went, the more routes you had competing against each other. Such that, eventually short distance freight became cheaper.
The same thing occurred with the roads, although not on a individual Sunday-drive level. You have a number of bus companies (which are fairly prevalent in Argentina from my knowledge. If I were to guess it would be because of some initial price shock, and mass transit seems to be a high-chance response for the market to have) and trucking companies that compete with routes to bring down toll prices.