You generally want some guarantees before you consume the service. Most would agree it is suboptimal if the first point you can assess the quality of your taxi

You generally want some guarantees before you consume the service. Most would agree it is suboptimal if the first point you can assess the quality of your taxi service is after being raped and dumped out of town (or waking up deaf because your doctor was an alcoholic, which happened to someone I know; the doctor was of course struck off). As to whether other systems like Yelp or Facebook are substitutes for the licensing process -- well, that is a reasonable argument to put forward. It's not the usual one we hear on HN though, which is just libertarian free-market-uber-alles ranting. One complaint I would have about using Yelp or Facebook is that they are private companies, and thus not accountable to the public in the way that government licensing services are.