1. I covered most of your complaints when I referred to the “great filter”.
2. It’s insufficient to say we’ve only been listening for 50 years. Why? For instance, if there’s a civilization 1000 LY away, if that civilization began broadcasting strongly enough in radio-wave bandwidths 950 years ago, we’d have heard them already. Conversely, no other civilization could have possibly heard our own broadcasts before 1920 (AM) or the late 1930’s (FM).

In other words, concurrence is the key.