Yeah kind of like how bacteria don't know they're under a microscope.

Consider your analogy stolen for future use!

They're all down there thinking "why aren't there any alien bacteria sending us some chemical messages already? It's clearly the best way to communicate"

H. G. Wells' analogy actually.

I love Wells. In what book might I find such analogy?

War of the worlds. Right on the first page.

Then we presume that all these advanced civilizations are somehow living peacefully together AND that they all agree not to mess with earth. That's extraordinarily unlikely. Evolution isn't good at producing life forms that peacefully co-exist.