This is, in my mind, the single most likely survival scenario that I might be faced with. We got stuck several times during the big East coast blizzard last year and would have been stuck for the night if I hadn't been carrying a snow shovel. From the article it seems like they were pretty well equipped other than that.

While I can't fault them for trying to honk the horn to get help, it's no surprise it didn't work. Many drivers don't seem to be able to hear a honking horn at all, and those who do mostly won't be thinking of looking off the road for the source.