When you are driving, you're, well, driving. Most of your mental capacity is on the task at hand. The remaining capacity drifts from subject to subject with not

When you are driving, you're, well, driving. Most of your mental capacity is on the task at hand. The remaining capacity drifts from subject to subject with nothing to anchor it - no note taking, very limited communicating. Your basic needs (mental rest, hydration, toilet) are pushed to a rest stop schedule. Every stop sign, right on red, or on ramp is a new negotiation. Even choosing your music is a big task leading you to settle for the radio. In a train you're simply transported sitting down. You can text, have a face to face conversation, look out the window, go to the toilet, buy reasonably priced drinks, read or work as you fancy. The occasional change between trains is a stronger punctuation in your journey than your car leaving the freeway, and still only requires a few minutes of cursory attention every now and then. Edit: I didn't even mention the timing aspect! In Japan you could get the same train every day and arrive on time every day. Commute on the roads and you will always be wondering when exactly you will get to work/home and what you will do with the little random slither of spare or lost time. Of course, the accelerator pedal is right there so you always have the option to drive a bit more aggressively, so you will consider it every now and then, rather than thinking about something more meaningful to your life.