[RWSen]

Because the water would need to be separated from the sand grains. The "water" in the sand is very little: it's more akin to damp sand we're talking about, or in the "wettest" case mud.

Drying that would require a lot of area, effort, and sun, or some type of oven. Any method of making sand drier costs orders of magnitutde more than the sand itself.