[AlotOfReading]

All of that comms stuff has its own logic associated with it that usually lives up there in my experience. In the past, manufacturers have tried to avoid putting much stuff above the headliner beyond roof windows and speakers. It's hot, narrow, and vibrates a lot (especially in the center). Frankly, the antennas are only up there because antenna placement is very expensive magic that doesn't deign to obey the whims of mere "designers".

Things are changing though. Autonomous vehicles need large numbers of sensors up there anyways and you can't keep shoving everything under the cabin.