People will absolutely provide negative reviews when they get screwed by a cab; they'll be sputtering and looking for anything they can do to equalize the situation.
But that doesn't matter, because this is the eBay problem; a reputation adequate to do business in the system is too cheap to establish from scratch to make losing one a major deterrent.
I didn't say people wouldn't leave reviews, I said they wouldn't have the same social incentive to do so as with other things that get reviewed. Other incentives (revenge) of course still exist, but the result is probably a heavy bias towards negative reviews, which can still make the system pretty unusable.
And this isn't necessarily the eBay problem, if you have to provide a driver's license or some other set of credentials to set up a driver account, and you can't just switch your handle in the system. The post was kind of light on those details.
(a) There will be more than one of these dispatching services, so you'll just hop.
(b) There's an inherent TOCTTOU problem, since they're only checking licenses when you sign up, not every time you pick up a fare. You'll just "rent" someone else's license; there are presumably tens of thousands of people who don't care what their cab dispatch reputation is.
Being able to switch services or rent someone else's credentials are different problems than being able to cheaply create a new positive profile on a given service. Switching doesn't help you much if there's one dominant dispatch service that everyone uses, and renting someone else's credentials drives up the price of scamming the system.
This is kind of a silly argument, though, because my main point was actually agreement that a taxi review system would probably be horribly broken. I just don't think it would necessarily be broken in the exact same way that eBay's is.
There are probably not tens of thousands of people with the correct license endorsement. Those who do have a commercial driver endorsement are probably not so keen to rent it out.
I don't think the average, I'm from east bumfuck, tourist will provide a negative review after being screwed by the cab. They aren't going to know! Yet they are precisely the ones protected most by the [broken] medallion system.
But that doesn't matter, because this is the eBay problem; a reputation adequate to do business in the system is too cheap to establish from scratch to make losing one a major deterrent.