Looking at the photo now I notice that balled-up little wad of paper. Perhaps it was a clue as to why the owner of the shoes had hot-footed it out of there. Maybe he was watching from a window or doorway waiting for someone to pick up the clue he'd left and discover him. Or maybe it was a prank, or a candid camera set-up, or just some random person whose feet were hot and sore. It's possible they intended to come back for the footwear, I suppose, and that's why they'd parked them in such an obvious place.
One of Life's Little Mysteries.