In a mind-boggling ripoff that went undetected for years, thousands of city cabbies overcharged nearly 2 million passengers by at least $8.3 million, according to a shocking disclosure yesterday by the Taxi & Limousine Commission. Officials said 35,558 of the city's 48,300 taxi drivers -- or three-quarters of all the licensees -- were caught overcharging at least once by secretly changing the meter's rate setting. A staggering 3,000 drivers swindled passengers more than 100 times each. A total of 1.9 million trips were overpriced. The scale of the thievery over the last 26 months was flabbergasting even to hardened veterans...