Motive (spoilers)
Having both read the book and seen the movie, I'm still left wondering what drove the village to become involved in the kidnapping, or indeed, HOW it actually came about. Certainly the village is poor, the drought must be affecting crops, and the parents are dreaming of better things for their families; but Salvatore's family for example are quite well off (especially in the book), no-one is apparently going hungry or suffering from their poverty, and Michele's family even have a television.
That Michele knows of no other life (and the results of the bungled situation) seems to suggest his father's involvement in crime is comparatively new (I searched in vain for information about his actual daily employment - maybe deliveries with the truck??). I just find little evidence in either text to justify or even explain the villagers' decision to kidnap Filippo, their subsequent callous treatment of a small boy over three months, and their ambiguous attitude that they are doing the wrong thing for the right reason...