Trust Issues

One problem that keeps people from using carpooling and other shared transportation is trust.  How do you determine if you can trust the person who wants to share a ride with you?  With auction sites a trust mechanism is built into the service.  

Perhaps you only want to deal with people who have a feedback rating of 9.  Another possibility is to use a trust network.  That is, I trust a certain set of people who trusts another set of people, and so on, so there is a transitive web of trust that can be used to filter who I ask to share a ride with.  This also works with shipping.  There are shipping sites already, like uship.com that have trust.  The problem is it takes a lot of people to use a service before the trust is workable.  A new service has both the problem of not many users, so it is unlikely that riders can hook up, but there will be little trust data.  If the ride share section of Craigslist encorporated trust, that might be a good option.  It may also be that trust could be used in a Craigslist listing, certified by a third party, something like squaretrade.com .