I can understand taking a human interest in other people's eating habits, we tend to measure ourselves against others. I dont understand how other peoples eating/drinking habits would upset a stranger though unless there was a knock on effect (drunkenness, abuse, morbid obesity, anorexia ect)
I could see why those examples might bother some people, but what I mean is why would anyone care whether I or anybody eats or doesn't eat breakfast. Or enjoys a nice hot cup of coffee while walking to work.
There seems to be a fascination for knowing what others eat generally, not just breakfast, judging by the number of 'what's for dinner/lunch' threads that appear regularly on AB.