I think the idea of how 'roads are paid for' is a red herring. Road tolls are not about drawing a dotted line from those revenues to the construction and maintenance of roadways. Tolls are useful for managing the dramatic mismatch in the demand and supply of highways. We can't practically add more more highway capacity in the built up part of the GTA. So demand will continue to ever increasingly excess the capacity, leading to worse congestion. Tolls would be useful for reducing that congestion even if they took all the money raised from tolls, piled it up and lit it on fire. Fortunately, they can be added to general revenues to provide greater benefit than that.