Eli5:How are so many radio waves transmitted simultaneously avoid interfering with each other? I get that they use different frequencies, but since the spectrum is limited and not all signals can be unique, why isn’t there more overlap and interference?

Eli5:How are so many radio waves transmitted simultaneously avoid interfering with each other? I get that they use different frequencies, but since the spectrum is limited and not all signals can be unique, why isn’t there more overlap and interference?