While corporate-owned roads are certainly possible, they would require continuous tracking of vehicles to charge them, and the tracking infrastructure would be a privacy nightmare and great additional cost. For the true solution, consider that all the currently needed roads have already been built by the government; the only required cost is to maintain them, and very rarely, build new ones. Upon transitioning to libertarianism, government roads will be transferred to the people, and maintenance costs will be paid for willingly by those whose lands are accessed via those roads.
Since a government already went ahead and used our taxes to build roads, we'll have to decide upon transition exactly how shares of the entities controlling different roads should be distributed among the people, and locals will have to plan collective payment for maintaining the roads. But it is doubtless that people will not let the roads leading to their land fall into disrepair, as it would discourage visitors to their businesses and homes.
That would be confinement. You can't just build a wall around someone and say, "Hey, I haven't harmed you or your property." You are still violating their property rights, more specifically, their right to access property.
The owners of roads are incentivized to set reasonable rules so that people want to use their roads.
