I thought the same thing, but then how good are the sensors we're looking with, really? Even the Hubble is a potato camera compared to a long baseline inferoterometer, which is a proposed space-based "hypertelescope", a virtual-lens that can be thousands or even millions of kilometers wide and would, if comprised of enough imaging elements, be able to directly image meter scale objects on or around the surfaces of multi-lightyear distant exoplanets.
We've only just begun to look, and no-one is looking for examples of hyper engineering yet, and as impressive as the Hubble images have been, our sensor-tech is still in its infancy, but once we really do get into space properly as a species, and can sic a swarm of of manufacturing robots on an asteroid and tell them to turn it into a massive cloud of linked space telescopes with 2030-or 2040 era sensor tech, then I would expect we'd eventually see blurry images of city lights on an exoplanet.
The interesting thing is, that maybe we are already seeing the works of Type II & Type III civilizations but we're not recognizing them as such. In 2004 Fermilab published the results of their preliminary sky survey to look for Dyson Spheres. It was a small survey, only about 10000 candidates examined, but out of those they found 17 stars that are impossible at present to rule out not being a full or partial Dyson Sphere.
And from the Type III department, Hoag's Object is a nearly perfect ring galaxy, but is a very unusual one in that it is extremely regular in shape and because rings are typically formed in a near miss or collision with another galaxy and there is no galaxy anywhere near it to explain it's formation, and further it's orbital speed is much to low for this to have occurred. The science fiction writer in me likes to think this galaxy is the result of a Type III civ or civs deciding to move all the stars in the thing out to the galactic habitable zone.
For what it's worth, my money is on us making some big advances in hypertelescopes, imaging sensors, optical tech and image analysis in the next few decades, and we're going to see the sky is teeming with stuff like this