As one who has taken taxis on a daily to weekly basis for the last ten years, I've never understood how on earth a Taxi Driver can pull scams on their passengers. I flag locally, call for a pickup, as well as take cabs from airports.
I've done this thousands of times in ten years.
In _all_ of that time, the closest I've seen to an errant fare (keeping in mind, I make the same trip hundreds of times with dozens of taxis drivers, as well as having Google Maps give me detailed distance information) is low tire pressure on a Taxi that took what should have been a $35 taxi fare to $38. It's amazing how little the "waiting time" charge varies a ride taken at a particular time. It's usually within 30-50 cents on a $40 ride at most.
I've never had a taxi driver try and determine if I was a "regular" or "out of towner" - and I rarely do more than just give them an address.
So I find it, based on my own experiences, very, very hard to believe that Taxi Drivers are engaging in any kind of widespread scam - unless they pull it on the blatant foreigners.
If I ever had a Taxi driver charge me the wrong rate, I wouldn't even dispute it with him, I'd just call their administrative oversight (which, in most cities, is the local police) and let them deal with it.
So, as much as people want to suggest "GPS Logs" are uncovering something - I'd have to suggest that by and large there is nothing to uncover. I'd be interested in seeing further details on these taxi drivers who have supposedly overcharged 100s of times - People like me would have flipped and/or called the police if they tried it even _once_ on us.
Color me dubious.