How about 1733 complaints against taxi drivers in 1 year in San Francisco alone? https://www.baycitizen.org/news/transportation/cab-complaint...
"San Francisco taxi drivers routinely flout the law by refusing rides, declining to take credit cards, charging unauthorized fees, speeding, smoking, and talking and texting on cellphones while driving, according to a year’s worth of passenger complaints reviewed by The Bay Citizen."
How many of those drivers lost their license, do you think?
There might be bad attitudes filtering down from the top and from handlers/motivators, but that's less about regulations and more about just being nice people. Taxi drivers could often do with the same improvement.
http://www.couriermail.com.au/news/queensland/taxi-driver-se...
http://www.ksbw.com/news/central-california/santa-cruz/santa...
Rude taxi drivers and huge detours to charge you more money are par for the course when it comes to taxis. Regulation doesn't fix this. I'm not sure what does, really.