Is the mic not in the central lighting console though? Making it in the middle of the speakers...

 

Having the speaker sound come from different direction than the talking to the phone reduce feedback issues. With digital systems like mobile phones the feedback will simply add "crackle cuts" or even cut all audio and in some cases cut the call.

So: local talker in one side, other end talker from one side (speaker) and mic in the middle. On top of that the mic is somewhat directional, picking up from driver's side more than passenger's side.