Multitasking is mostly for those who have muscle memory in driving home to work and back. I have a hard time remembering going to the grocery store on the way because of muscle memory

zoning out while driving doesn't mean you should pay even less attention to the road

Muscle memory is good, until you get unexpected unexpected.

I remember an experiment about driving there the subjects had to go to a simulator and drive the same simulated route for some time, until they know it and it got boring. So, after a few days, suddenly a deer/pothole/kid/car/whatever appeared.