Just because! If we take the mic out of driver's hands, you put everyone out of business... PD, FD, EMS, delivery, taxi, yada, yada, yada. While I know the point can be argued, talking into a mic is not as distracting as talking on a phone. With all that said, this is why some jurisdictions (my first life job, DC included) call it "Distracted Driving". When it first came about in DC, we were taught that it applied to anything that distracted the driver... eating, tuning the radio, make up in the mirror, etc.