Hidden, at least, until you need it. These outlets are designed to blend into their surroundings by exploiting architectural blind spots: They are low to the ground, unobtrusive in color, and, most importantly, blend into the vertical line of the single tree and horizontal line established between the trees.
More than this, we are taught not to notice infrastructure, to ignore outlets and pipes. We are taught to experience spaces as humans, not as electrons or water molecules. We must learn to see buildings infrastructurally.
Of course, outlets can also hide under things, like bushes or overhangs. The surroundings of the outlet are less important than its proximity to expected needs.
(This post, drafted waaay back in August, also represents This Material World’s first brush with the law: A UVillage security guard stopped me to ask what I was taking pictures of (“Um, the outlets.”). Fortunately, he was also an architecture major at the University of Washington.)