As someone who grew up in a poor area, where "eating out" for my family was getting a pizza or steak burger or something like that, there is definitely something to be said for 'exposure' to different types of food.

After I left for college, I was exposed to all kinds of foods for the first time - olives, mediterranean food, Japanese food, chopped salads, and so on. Now, when my family comes to visit me in NYC, they like trying lemongrass grilled chicken, noodle dishes - all much better than endless pizza (though I still love pizza).

My point is that 'demand' is not such a simple thing. There are so many different types of foods, many better than fast food, some worse, whatever. But if there were policies created by the affected peoples (as it seems in LA) that incentivized the introduction of different types of food, 'demand' might change in radical ways - and for the better, too, in terms of people's lifestyles and health.

Or not... it could all fail terribly. Maybe the ghetto and Thai cuisine were never meant to mix, haha. I doubt it though! But I don't see the harm in trying - again, if it's done with the affected people's input and consent.