Panting a fence, not art because it keeps the wood from rotting.
Painting a fence hot pink? Art because there's no good reason to paint a fence that color.
If we discover that birds hate hot pink fences, and that makes them last longer? Not art again.
A rich guy pays a million dollars for a hot pink fencepost? Art. Who's the guy who sold the hot pink fencepost? Does he have any other colors?