I recently visited Roswell, NM, and was surprised at how many flight tests have been performed there. Even the fatal Gulfstream flight test crash happened there. My research shows that a lot of flight tests happen at places like San Bernardino, Roswell, Fresno, and Moses Lake. My research turned up only simplistic explanations for why these airports are so popular like "Boeing chose the San Bernardino facility because of three factors: hangar size, availability and weather." (Source: The Sun News) Is that really all they consider in determining flight test locations?
I've heard that you can't do flight tests at just any airport, though I haven't been able to find any relevant legal restrictions. The airport choice doesn't even seem to be just the obvious factors like weather, runway length, and GA availability. (I also don't care about specialized testing that would require unusual airports like long runways or specific temperatures.) There are a few dozen low-volume long runways in the arid American West and similar regions. Why are just a few so popular? Are there any FAA (or EASA) restrictions on doing flight tests at any old airport?