The diagram, as shown above, is a proposal for how we should tag motorways and other toll roads.
We use toll=yes for motorways or roads that lead directly to and from toll barrier.
We expect a majority of motorways to be a toll road, so for consistency we use tag=no for motorways that have no tolls.
Motorways or toll roads do not immediately become toll=no after the toll barrier, and not until the next junction as shown above.
We ignore roads that are not accessible to the public when deciding whether a section of motorway is a toll road or not.
In this way, we show the extent of the toll roads in a reasonable way, and avoid marking sections as part of a toll road when it really isn’t, and vice versa.
The wiki is currently read-only due to maintenance, I will upload an SVG version later, with the corrected diagram as the middle dot should be a toll on both directions.
Debugging map: http://product.itoworld.com/map/246?lon=22.49689&lat=37.61657&zoom=8&fullscreen=true