as
@dwfaust pointed out above, something should not popup when directions are being given. The phone should be allowed to be used minimally by drivers, only for things like navigation; that too when the directions have been fed into it before you shift into "drive". (disable all other distractions at that time like icloud, notifications, etc).
How exactly to differentiate between driver vs passenger - there's no clear cut answer as yet, but some ideas I can think of from the top of my head: some kind of low power field which emanates from the steering wheel and encapsulates the space of the driver's seat. The phone can read this signal and disable almost all other functions. Or maybe a camera above the driver's seat which does object recognition and sends a ping to a nearby device.
While the car is being driven, phones should automatically transition to a "driving" state. You can program them to automatically change the voicemail to announce "I'm driving" or auto-reply to any incoming texts saying "driving, will reply later".
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first of all, if you use a phone while driving and endanger others, you've no taste, in life. See, others can play that game too.
But on a serious note: If you're so realistic, can you be honest and tell me this: if given a legal document today, which states that if you ever find yourself or a dependent of yours in a situation where you're injured in an accident or your dependent is killed - and its proven in court that the accident was entirely the result of distracted driving by some driver on a mobile device, you will refuse to not only file a case, but even get any kind of damages. Secondly, if you're badly injured and need medical attention, you don't have any right to medical treatment, since you're "cool" with talking or texting or fiddling while driving. Are you prepared to be "real" and say that you will sign this? If so, I salute you. Most of us will not. If not, why not?