This is a start... defining the how-we-eat question. I keep thinking it's very clear. I say, "I'm interested in the casual eating spectrum." And people go, huh? I needed to define my terms, how do I define the quality or range of what eating is. Where and how it's served makes most sense - the space and service (or lack of).
My scope is American metropolises. Specific cities on the West coast, East coast, and Chicago to rep the mid-west. These are not random, I've "lived" in all of these cities. (I'm stretching that claim a bit... I haven't lived in Chicago, Boston, or New York but close enough)
Age and class are considerable factors, however I won't be addressing them here. I will politely decline to go down those rabbit holes. Here the focus will be on how to access value in casual eating, not much more and not much less.