Actually there are two other important differences as well. 1. We operate in an almost exclusively financially driven market, with customers paying for product from vendors. Child pornography collectors operate in an almost exclusively non-financially driven market, with images freely distributed. 2. Demand drives supply in the case of drug production. Nobody would grow marijuana if not for the demand for marijuana. On the other hand, in the case of child pornography the link between demand and supply is much less established, especially in cases where there is not payment for the pornography (in cases where there is payment there is often times a clear link between demand and supply, so there are good arguments for criminalization of paying for child pornography, and certainly paying for child pornography production should be illegal). Child molestation took place prior to the existence of child pornography so it is obvious that demand for child pornography does not entirely drive child molestation.