While the 1.8 million overcharged trips is a large number, it represents only 0.5 percent of the 361 million taxi trips taken during the 26-month period the agency studied.
Given the tiny percentage, I think calling it a "scam" is a bit over the top. Who doesn't make an occasional mistake?
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A single cabby was accused this month of overcharging passengers a total of $40,000.
On the other hand, this was probably not a mistake. But in many cases, I would guess it was an innocent mistake.