[mrweasel]

Ride sharing doesn't really work, because it assumes that people have very fixed patterns. I get into work at 8 in the morning, but I leave somewhere between 15:50 - 17:00, depending on what happens to land on my desk that day. Finding someone who's going my way, and willing to wait an hour for me to finish up is going to be hard.

Also I might have errands to run, team sports (or I may not, depending on the weather). OR how about you having to leave early, because you have to pick up a sick child from school? Current ride sharing leaves you stranded or unable deal with unplanned events. That's why people drive.

With driverless cars, that can pick you up on demand, some of these issues go away, maybe, but how do you coordinate sharing a random ordered ride with someone? How long are you suppose to wait, before the car decides that the other person is now late, and takes off without him?