Well, aren't babysitters usually kids? When I read this, I assumed she meant that ordinarily they would have driven the babysitter home, but couldn't under the circumstances.
Hmm. I don't know if most babysitters are kids. Don't the Soledad O'Brien's of the world generally have nannies and adult sitters? In any case, I've heard the locution used by people who were not referring to kids.