"""I don't drive with the radio on any more"""
On long drives, it's generally recommended to keep the radio on to fight fatigue. Maybe you get more distracted by music than I do, but wind (white) noise tends to tire you (well, most people) rather quickly, so covering it with something intelligible helps a lot.
And driving really isn't so hard that it needs your full attention any where near 80% of the time - I spend far more than 20% of my driving time stopped at lights, and it doesn't require intense concentration to tell when the 8 people in front of me begin to roll forward.
If you've been driving for a while, and you're used to your car, picking a course and steering onto it should require minimal thought and effort, and most of the time conditions really don't require anything more than moderate alertness to notice and respond to unexpected events.
I'd say that occasionally, when there's low visibility, low traction, unpredictable drivers, unfamiliar or complex interchanges, or poor signage, a driver needs to pay attention 100%. If you can't drive safely in easier conditions with a few added distractions, then there's just no way you can reasonably be safe in difficult conditions with no distractions. Plus, maintaining a high alertness level also leads to fatigue.
Fatigue, by the way, is also quite deadly behind the wheel, and it can be sneaky, which is why I concentrate so much on avoiding it.
Around here, almost nobody pays attention - while I wait at those lights I watch other drivers complete their left turns and then almost at the same point on the road most of them look straight down into their laps, where they're trying to hide their devices from the cops.
And I think they should all have their licenses revoked.
I'm OK with a hands free call (no, holding a phone on speaker phone 2" from your face isn't hands free,) but any activity that requires looking away from the road for more than ~2 seconds seems like it should already be illegal under various reckless driving laws.