Odd that you should mention soaps, as that comparison came (differently) into my mind when I was reading an earlier exchange on this thread. There was a discussion about the recurrence of similar 'plots' (or narrative themes) in different ballads, and this brought to mind the way in which different TV soaps often seem to sprout similar storylines. Coincidence, or creative copying, or maybe there are just only so many permutations of the highs and lows of the human heart.