I suspect the reason we don't detect any sign of technologically sophisticated alien life is due to a few simple factors.

One: if life on Earth is any guide, most life will be the equivalent of prokaryotic, so it will never emit any communications signals.

Two: again, if life on Earth is any guide, any eukaryotic life is likely to be marine and thus conditions will not permit the development of any significant technology (this is why cetaceans haven't invented smelting).

Three: the vastness of time and space means that the likelihood of any two technological civilizations existing within feasible distance of each other and having the economic resources necessary to sustain any kind of outreach is nearly zero. Imagine if some other species 40 light years away was sending out signals as recently as only a million years ago (less than the blink of an eye in cosmic terms) - we weren't there to hear them and equivalently no one is there to hear us now.

We forget the problem of time & space because we've all seen far too many sci-fi entertainments. But TV and movies are very unreliable guides to reality.