George Harrison's 1971 song "Bangla Desh" was the first major charity single. It was part of a concert held to bring relief to the people of Bangladesh, who were fighting for independence and suffering from a famine.
Who writes a song about a name they found in a phone book? That's just one of the everyday things these guys find to sing about. Anything in their field of vision or general scope of knowledge is fair game. If you cross paths with them, so are you.