This falls under the "You have got to be kidding me!" category.

The nav unit and the radio are built together in this unit (one solitary power button), if you select the full nav screen and the volume of the radio all the way down or hit mute then the radio may just as well be turned off for any and all practical purposes.

Other than to satisfy some strange sociopathic thought process, what difference does it make? I mean really, think about it, what’s the big deal?

 

That is my exact thought. I mean, it makes sense to not have to push a separate button for the radio...doesn't it? It takes some getting use to but as EscalonJon said, this is my first nav system too and I am still getting use to it.