I'll bite. How in the world do you consider driving to be wasted time? Don't you think while you're driving? Don't you work through problems in your mind? Don't you rest, listen to music/radio? Don't you have interesting discussions with fellow passengers?
Here is my reasoning. You can do the activities you mentioned in places that are a lot more comfortable (sofa), more social (cafe) or more beneficial (gym) than the driver's seat.
More importantly, I don't trust my brain's thread scheduler to drive with full attention and think about something else productively simultaneously. How many of us can say that they have never been in a dangerous scenario because they were lost in thought while driving?
