I MCed a game (incedentally we had three vehicles and three players) where the players had radios all over the place. I played in a game where no one had any radios, nor any real need for them.
I played in another game where we DID have radios, AND a need to use them, but we never used them because I didn't trust the guy who set them up. Yeah, my character sat in one place, next to a radio, and the others still had to come and talk to him in person because the radio wasn't on. (And because I couldn't kick their teath out over the radio.)