I figure this would make a great phone app.
Logon, add a picture, possible finger print
Now the system knows who you are, both driver and passenger. Both can post their desire. Both get to see each others profile and using gps where they are. i.e. how close.
If ride is excepted the system records time, date and info on the grouping. When group is split, that is recorded also. A comment section that travels with the profile so you can comment on your experience.
Now this may not stop something bad from happening, but it would sure let the authorities know who was with whom. I also thought the system could gather enough personal data to run a simple background check. Service would be free and pay for itself with ads around the gps point.
If it is after 5:00 when I post I reserve the right to disavow anything I posted.