Damn, this is basically what I was going to post. We have to point our telescopes at a point in the sky and gather light for hours or even days just to see the faintest image of the brightest and most energetic events in the universe. Catching a signal from an alien civilization is just insanely unlikely. Not to mention, while life itself may be common, highly evolved sentient life capable of putting signals out into space is probably unfathomably rare.