This is waaaaay to simple of a depiction of modern roads. Modern infrastructure is super complex, with roads going down meters with many different layers and components.
I would recommend the Practical Engineering YouTube channel to get some insight in how complex our modern infrastructure actually is. Things that seem so simple on the surface are often really complex.
Also: roads aren't designed for cars, they are designed for super heavy big vehicles carrying tons of materials. If the road can handle those, the cars don't really matter all that much.