Actually, if you look at a freeway, the main wear is in pretty centralized areas. Most of the surface goes pretty much unscathed. Local highways are generally wider than necessary, and much of the surface would remain rather infrequently used.
I do see some concerns along the lines of what you mention, but I’m not convinced they’re deal breakers.
Certain costs associated with roadways would be eliminated altogether. Some of those reductions could be used for repairs. And if the energy production reaches it’s full potential, this would by far more than pay for itself.
The “main wear” area being near cities where you need electricity. Although the hinterlands have their own problems, the ever popular desert brown road.
I don’t think any of the costs of roads go away, they’re going to have to sit on something, which will have to have all the usual flattening and sealing done to it. Basically you’re looking at a road with a much more expensive top, and more manual labor to put the top in place, and it’s less durable. Very little chance it generates enough electricity to come near offsetting itself.