Storm drains, aqueducts, and swimming pools are typically made out of concrete because it has the right properties to deal with lots of water. Roads are typically paved with asphalt. Unlike concrete, asphalt is far more subject to damage from water.

One of the main purposes of crowned roads is to ensure that water flows off the asphalt quickly in thin sheets that don’t cause erosion. A heavy flow of water on asphalt causes too much erosion. Also, pooling or standing water seeps into asphalt and causes damage and structural problems. Especially in areas where the temperature gets low enough to freeze.

There are also other problems with V shaped roads, but avoiding water damage from pooling and erosion is the big one.

Slightly V shaped roads are used where cars don’t go, like in pedestrian shopping centers with outside walkways.