If I try to do voice commands while driving my field of vision narrows to a pinprick.
Honestly, on 101 and 280 I see drivers texting all the time and they're driving right in the lane, no problems at all except being slow to react to what happens in front of them (which makes it obvious they're on the phone). I don't know how they do it. Even glancing down at my phone instead of the center console loses so much state.