Ronnie Dunn wrote "Boot Scootin' Boogie" before he teamed up with Kix Brooks to form Brooks & Dunn. It was originally recorded by the country group Asleep At The Wheel, but Brooks & Dunn did it themselves when it got its own line dance.
"St. Elmo's Fire (Man In Motion)" was not written for the movie, but for Rick Hanson, a wheelchair athlete whose 1985 "Man In Motion" tour logged 24,856 miles on his wheelchair in 34 countries while raising $26 million for spinal cord research.
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.