IF planets are actually hollow it would explain a lot of things. How civilizations survive such impacts, for one. Where “Eden” is, for another. Why we can’t find high tech radiation traces in the solar system, let alone from other stars...
Where lost socks go... where new wire coathangers come from... the real source of velcro...
It could be that radio transmission is a short lived technology in the ascent of any civilization, and that, given different rates of advancement, and the inconceivable distances between stars, that it is rare that two civilizations should be at the same relative level of technological progress as to intercept the other's transmissions. Some may have already nuked themselves into oblivion. Others made it to the other side where all the good stuff is - some kind of quantum communication or innovation that we can't even imagine.
It might not occur to advanced societies to use radio any more than it would dawn on us to send up smoke signals. Ain't nobody got time fo' dat.