It costs around $600,000 to pay for a license to operate a taxi in New York. Is it easy to operate one without a license? Could you get away with it? It seems like there are so many people and taxis in New York it would be easy to get lost in the crowd.
I heard about people making a good bit of money with fake taxis. The real problem is the taxi drivers themselves will just about murder you if they find out, and at the very least report you and have you arrested. It's ridiculous. They act like they own the job. Just another monopoly union using state power to artificially limit competition :\
https://www.nytimes.com/2012/03/20/nyregion/expanded-enforcement-of-taxi-rules-leads-to-seizing-of-livery-cabs-outside-manhattan.html?_r=0
http://newyork.cbslocal.com/2012/05/15/seen-at-11tlc-officers-go-under-cover-to-bust-illegal-cabbies/
http://newyork.cbslocal.com/2012/02/23/nyc-cracks-down-on-illegal-cabs-could-take-many-more-vehicles-off-street/
The Taxi companies don't like you impeding on their monopoly. Also, this talk of illegal taxis reminded me of this one video (sadly I wasn't able to find it), which had a police officer seeing tourists get into an "illegal taxi", he ran over and leaped through the driver side window in order to pull the keys out of the ignition and save the tourists from the ghastly outcome of................ getting driven to their destination.
Edit: Also, check out this article:
http://arstechnica.com/business/2012/09/my-life-as-a-high-tech-part-time-not-quite-taxi-driver/
I posted about this a while back, I'm not sure if it's expanded to NY. They get aroud the San Fran medallions by asking for donations instead of charging. I assume they log who every customer is via their phone/credit card so while someone can get away with not paying once if they do so noone would likely ever pick them up again.
http://techcrunch.com/2012/06/26/sidecar/