LOL, I think those who can eat that outsize burger must have those expandable jaws similar to the kind that snakes have.
Here's the funny part: I grew up thinking a sandwich was two triangles of buttered bread, crust trimmed off, with a couple of slices of cucumbers or tomatoes as filling, or perhaps a little chicken. The sandwiches I saw in this great nation truly left me gobsmacked. I had the same question Howard asks above: How on earth do they eat them?
A similar revelation happened to me in reverse when I went to Italy and had their pizza for the first time: Conceptually, it was rather like my sandwich in India. A thin crust of dough with a bit of marinara sauce smeared on it and some melted cheese. Amazing, after consuming our American variety which is like a disc of dough with a small forest of toppings.
I suppose food reflects societies and cultures in interesting ways.