From other accounts, people back home are generally too poor to come looking.
These people have to smuggle themselves out of their own country, then maintain a presence illegally abroad, then run an amateur investigation. It just doesn't work out like that.
I live in a rich European country and every once in a while they find some poor smucks forced to pick asparagus at a farm or have sex with a dozen men a day in a hotel. It gets a little column in a newspaper.
It's really not that hard to make people drop off the grid in an uncaring world.
These people have to smuggle themselves out of their own country, then maintain a presence illegally abroad, then run an amateur investigation. It just doesn't work out like that.