Why the heck don't French child protective services, in whatever shape or form they exist, come into this place and remove unaccompanied children into their care? In fact, it should look at the danger this environment poses to all children. What do French authorities do ordinarily, if a child is in danger of abuse or being trafficked? I would be surprised if they were normally left in danger as appears to be the case here. Do France not have foster families, children's homes etc. like in the UK?
If they are on French soil the state shouldn't neglect it's duty of care and leave them in such danger. There is absolutely no excuse to leave them in that environment. Any asylum applications or request to join family could be made from France. In a safe environment.
And why aren't the traffickers being caught and prosecuted?