? We don't have self-driving cars either. And arguably, driving a car requires more attention, even when in a "robot state" than walking will ever.

Sleeping/sitting is the only thing I can think of that you can't do while walking (that you could do in a car, i.e. not tivial exceptions like 'visit the Sydney Opera House while walking the Appalachian trail') - it's basically an autopilot thing anyway, only breathing bests it.