My step-dad was a NYC cab driver. It's true that they're a small percentage of the population, but that's not the right way to think about it. In NYC (and other US cities as well I believe) to become a cab driver requires buying a Medallion, which is a license to operate a cab. They cost a LOT of money, roughly the same as a small NYC condominium. My step-dad's cost a couple hundred thousand dollars many years ago, and Wikipedia[1] says they can cost over $700k today. They used to be mostly individually owned, but today, because of the expense, they're mostly owned by fleet operators.
The individual owners of these medallions are small business owners, and those who operate cab fleets are large business owners who employ many drivers. Automated vehicles aren't just going to put some people who drive out of work; they're going to eliminate an industry and destroy investments in a lot of businesses.
Or, maybe not. The TLC (Taxi and Limousine Commission) in NYC is a powerful lobbying group. They'll probably fight to prevent automated taxis in NYC until they're proven, without a doubt, to be safer than experienced taxi drivers. Then, they'll fight to ensure that an automated taxi requires a medallion just like any other taxi. Very few new medallions are issued each year, so the onus will be on the existing taxi owners to convert their cars into automated cars. That's probably a good deal for the individual owners, since they're usually either the drivers as well or they're paying a driver (or both, to keep the taxi on the road as much as possible.) Automation will get them out of the drivers seat, while still preserving their investment. But this is a bad deal for the regular drivers who aren't owners; they'll either be out of work, or maybe paid (less) to sit and ride along until passengers get used to the automated cars.
[1] http://en.wikipedia.org/wiki/Taxicabs_of_New_York_City#Medal...