What's also interesting is small proportion of Thai's compared to the number of Thai restaurants. It appears that there as many Thai restaurants as Vietnamese restaurants despite far lower Thai immigrant populations.
Around here, many Thai restaurants are run by Chinese (I know since Chinese dining partners claim they are speaking Mandarin in the kitchen). Some of the [bad] takeout joints just sprinkle red paper flakes and peanuts on lo mein and call it pad thai. To extend this, many cheaper sushi places are Chinese run, and cheaper Indian places are Bangladeshi run (which is why I always look for a turban when I want north Indian).
Where I used to live, the Vietnamese places were mostly run by Hmong (and a Hmong friend told me that the food at one place was really Hmong + some phos).
In short, there is little correlation between restaurant genre and chef/owner.