On the other hand, for many people, having to talk to a security guard and move to the lane on the other side is a non-event, and they might have tried to talk to the guard even if there was absolutely no need for it, if they felt it wouldn't be an issue for the guard (not too busy, looks bored etc.). Efficiency could be super low on their priority list, if it wasn't they'd be paying a lot more attention to the signage in the first place.
In my mind if I'm an adult person in an airport and I missed obvious signs and just went with everyone I'd be genuinely thinking about this for days and softly beat myself up, look up the airport floorplan and for years after in every airport I would think about this.
This is not a hypothetical for me because it has happened and I'm still triggered about it to the point that's years later and I'm here typing about it.
GP was only saying that going with the herd is most of the time a more successful strategy, and even if I don’t follow it, I’m not blind to my selection bias to say it doesn’t. As he stated, it wouldn’t have been selected otherwise.
I'd rather be wrong on my own decision than on one I blindly followed from someone else :)
And it's not about going against the grain. It's about making conscious decisions rather than blind following. The outcome can very well be the same as everyone else's of course.
So, just looking at the final result they ended up in the right place ?
Assuming the security guard made that adjustment because they were so many of them, the strategy seems to be paying off in that specific case.