I've refused to pay for, and reported to their company, 4 separate drivers in the past 2 years for this practice. I have to assume that the companies somehow don't care that their drivers are going rogue, or else this wouldn't be happening so frequently. Where is the threat of dismissal, or even better, prosecution? Same thing goes for unlicensed taxi drivers moonlighting with a friend's car - taxi drivers here are required to hang their licensed ID on the side window, and the frequency with which you find someone driving "off the books" is downright reprehensible.
The worst part is, I feel my personal safety is at risk every time I report these criminals. They are likely to know it was me, and they know where I live. It's irresponsible, potentially dangerous, and unacceptable to permit them to operate in this way.
Our taxi companies are hook, line, and sinker in the pockets of our government. We have a history of corruption here, and taxi companies are definitely part of the equation.