Jon Lucas wrote: I cannot understand how what is effectively a public road (even if privately owned, managed and financed) can be allowed to stay open without planning permission.
Two very different perspectives here. You view a road as a physical entity which is constructed. When new ones are planned they go through a long consultation process. One cannot be built without permission. That is the modern experience of creating motor roads.
Most highways however were never planned as such. They merely evolved through long custom or landowners' acquiescence. At the most basic level a highway is just a right of passage and our legal system still largely views highways as rights rather than things. As each landowner can use his land as he wishes, he is free to allow or charge others to use it. If he can choose to allow or charge individuals he can choose to allow or charge the public at large. The state would need a good reason to interfere with an individual's rights over his own land.