Yet even their "Anarchist" (lower right) square has a rectangular item of food, with a starchy, finger-friendly exterior around a less starchy & finger-friendly interior.
Vs. a chart with chocolate-covered cherries, ceiling tiles, and such...
Agreed. One point of contention I've seen before is the question of whether a piece of fried chicken with breading is a sandwich. Personally I argue that it is not, because the batter is cooked for the first time on the chicken itself. The starchy finger-friendly exterior should be fully edible before the construction of a sandwich.
You could argue, however, that a piece of fried chicken with breading is technically a meat bun.
I will proclaim that the finger-friendly exterior is important, but the order in which the outside vs. contents are added/cooked/finished/whatever is not.
So well-breaded chicken is. Likewise a two-crusted pie. But a ravioli is not a sandwich.