Buried within Jen Kalb's very insightful response on the Outer Boroughs board (see link) is an interesting observation. She writes, in part,
"But with a "successful" cuisine that goes mainstream, you start to see shortcuts, and an evolution away from the genuine. It may take a while - the thai restaurant with thai cook and chinese helpers - the chinese helpers learn enough to open their own "thai" places, maybe with mexicans in the kitchen...the chinese owned and operated mexican places..."
Regarding that last part, surely you're not saying that one must be a native in order to cook authentic cuisine of any type, even ethnic cuisine. Authenticity has to do with flavors, textures and techniques, all of which can be learned. Of course, immersion in the native culture is an ideal way of doing this (whether through growing up therein or cooking in the region of choice for an extended period of time), but I don't consider it the only way to do it. Easy examples are non-French chefs who cook French cuisine of one type or the other or someone like Norman Weinstein who dedicated himself to learning about various Chinese cuisines.
I expect your specific reference is to the enterprising folks who opened the first Fresco Tortilla chain in NYC. I have no problem with their decision to learn Tex-Mex cuisine and open their own place. And for the money, I think they do a very good job. What makes them any different from someone like Bobby Flay or any other chef who has adapted (and adopted) a cuisine from another region from where they grew up and make it accessible back home? Perhaps you're saying the danger is that people come to expect that what they see is in fact the way it is cooked in the particular region -- but as we all know, even within that region there are tons of variations (due to economic status, market conditions, etc.)
Perhaps in this day and age, authenticity is in the eye of the beholder.