I would assume that this reflects how eating remains more of a social ritual in some cultures rather than a solo refueling mission, as it frequently is in the U.S. It reminds me of my experience in Europe, where I found to my chagrin that the idea of getting coffee to go is practically unheard of. In New York, in my neighborhood, the Greek immigrants sit at the cafes all day and I can't even figure out what could be keeping them there. I find, sadly, that I relate more to the people I see shoving a slice of pizza into their mouths while walking through crowds in Midtown.
But our feeling of perpetually not having enough time seems to rationalize such behavior. Eating quickly, which almost automatically means eating alone, seems a consequence of the enormous pressure we feel to be moving on, consuming more, shrinking the base unit in which we measure the attention we pay so that we have more of it to spend. This need to economize attention (where does this need come from? can it be resisted?) encourages to isolate ourselves so that we may have complete control over our "experience economy". It also prompts us to gird ourselves with gadgetry so that we may streamline our cultural throughput.
Perhaps since Vance Packard and his ilk first made a sensationalized stink about planned obsolescence in the 1960s, it has seemed inherently subversive to slow down or prolong our consumption time. But the time we spent consuming something doesn't seem to be something we can set out to control; it instead seems a byproduct of our engagement with the thing in question, which makes it an insidious target for manipulation. The result is that conscious efforts to slow ourselves down may make us feel intolerably bored with ourselves.