Given the number of people who have asked me for directions at airports while standing right in front of oversized signs, and the number of people who have asked if I could validate their parking ticket or help with their luggage at various hotels purely because I was wearing a uniform, I would say that there are a frightening number of people out there who need all the help they can get. Hence the need for boarding cards.
Darwin's ideas on evolution has been suspended for quite some time when it comes to humans.