Dead Parents.

I read a great many detective thrillers. I have nearly had enough, though, of the convenient and ubiquitous device of killing off all and any inconvenient parents. Time and again, these are disposed of, usually as a pair, by: air accidents, car accidents and, typically, landslides. I don't really get it. (Perhaps I shall have to utilise this valuable literary method in my next novel - but if I do - it will, of course,  be attempted ironically.)