If I remember my 2nd year Fluid Mechanics correctly, the reason for potholes on the road is stagnant water. Specifically, the fact that (for practical purposes) water is incompressible.
If the roads do not have proper drainage then the rainwater collects on the road. When a vehicle passes over a pool of water it exerts pressure over it.
This pressure is in turn transmitted to the road. As more and more vehicles pass over the stagnant water, the top later of the road becomes weak and we get our wonderful potholes.
Perhaps having a basic drainage system in place would ensure longevity of roads. But then, if the roads last twice as long then the contractors can only rip us off half as much!