"Simply leaving your phone/tablet BT radio on doesn't result in spontaneous connections and transmissions of random audio data."
It can, and there are instances reported here of PC BT being left on causing Alexa to speak.
Parker, I do not want to discuss the technicalities of radio waves, microwaves, Wi-Fi waves, residual microwave radiation still mucking around in the Universe since the Big Bang, or even ocean waves, in an Echo forum; plain and simple. I made a comment, you made a comment, so let's move on so we can assist people get the most from their Echo products in the most simplest terms.