Caption: A simulated Airy diffraction pattern with intensity in grayscale.
Features:
If λ << L (where L is the characteristic length of the aperture or obstacle that cuts the wavefronts), then the diffraction pattern alternating dark and bright fringes are very tiny about the bright central fringe which approximates an ideal beam of light rays.
So the diffraction patterns at the edges of shadows are usually too minute to be observed by casual observation.
But actually, we'd notice them pretty often if they weren't generally partially averaged away as discussed above.