heads-down tribe

Jargon for groups of people with their heads angled downward because they're looking at their smartphones.

Historical perspective: Best described by William Falk in The Week in November, 2013, "Are we the masters of our technology, or is it now our master? You cannot escape this question even while walking down any city street, where the zombies of what South Koreans call the “heads-down tribe” troop along, mesmerized by their smartphones."