This from a pal:
My wife is the one that makes sure we have passports and tickets when going away. Once on a flight when [name] was just two, they boarded an airplane to discover there were only single seats. Naturally my wife wanted to sit with [child]. She went up and down the plane asking if anybody would accommodate, but nobody would. So she took [child] and put him in the centre of two guys who refused to move. She said she hoped they'd have a good trip and they were good with screaming two-year-olds. They suddenly decided to give up their seats.
As it happens, the boy was not a 'screamer' and is very mild mannered but it shows that some people do not understand the problem.