How people behave in crowds.
I am sure there must be some science that people switch off and go onto auto-pilot when many others are around, as if it is some sort of safety in numbers mindset or whatever. The lack of awareness is mad.
Waiting to get on a plane just now and one person stands up to go and start a queue to get on the aircraft. Not a single member of staff has done anything to indicate we are about to board, no change in signage or announcements, someone just decided to go and stand at the front.
Another 40 or 50 people then get up from their seats, collect their belongings, and go and start joining this imaginary queue to get on a plane where they already have an allocated seat assigned to them.
They've now been stood there for 10 minutes at least.