"Piano Man" was inspired by Billy Joel's time playing at a piano bar in Los Angeles. The "real estate novelist" was a guy who always talked about writing a book, but spent all his spare time in the bar.
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.