We keep looking in the radiation bands for communication methods. Because the speed of light is finite these don’t seem to be the most efficient for light year distance communications. A extra terrestrial species with the ability to communicate outside of their own space could be communicating in an entirely different manner. Maybe they’ve untangled the nature of ‘dark matter’ or have mastered interdimensional access.
My point is that the galaxy could be densely populated and we wouldn’t know it because we’re only considering that life will communicate on the EM radiation band. But the universe is not only stranger than we imagine, it’s much more strange than we have the capacity to imagine.
Yep, it’s like looking for smoke signals... Ain’t gonna find any.