How closed-minded can you get ??
These people are stuck in a horrible existence. This offers some money for them and a fascinating experience for the tourists - what's the problem ? It's a win-win. You keep going on about "It's Illegal" - so is jay-walking but no one ever gets busted for it. Are you aware of even one of these tourists that have been arrested for taking the "illegal" tour ? Don't try a scare tactic when there is nothing to fear.