I have some questions on group hiking dynamics as well, as lost hikers seem to happen often enough on group outings: who was leading this hike, meaning not who was in front of this group, but who was bringing up the rear? Were there other hikers behind him, was he the effective leader? If others were behind this lost hiker, were they so slow that he was able to take a wrong turn and not be missed by those behind him? Was there even an attempt to buddy up on this hike?
It would have been more difficult to get lost if the lost hiker - and all hikers in the group - had paired up before setting out. And if the group as a whole has a sweeper, whose job was to be the last person out and try to keep an eye for hikers venturing off the assigned trail. That means no matter how slow the slowest hiker, that sweeper (and his buddy) is still behind them.
Worst case: two lost hikers instead of one. Assuming one of them had better eyesight that the other, they might have route-finded their way home.
Works in Scouts while riding herd on 11-15 year olds, I wonder why folks don't apply it to their grown up hikes more often.