It could also be that there are a series of different communication technologies. By the time we move onto the 3rd, noone is listening for the first. For instan

It could also be that there are a series of different communication technologies. By the time we move onto the 3rd, noone is listening for the first. For instance AM radio, FM radio, TV, Spread spectrum analogue, digital, ... hypersuperfastwave ... Since each tech spreads from the source in a small sphere-shaped shell depending on when that technology was invented, you need a huge co-incidence for someone else's shell to hit you WHEN you are listening for that type of communication.