Cluelessness?
You are correct in that that sex trafficking extends to indie providers. A lot of fast houses uses the same girls in rotation as spas. But they are also correct in that odds are better you will run into a true indie. One that's here on a tourist visa trying to make some fast cash, and isn't doing it against their will.
Either way, I'll second
@dirkjones and say to not consider this aspect of the business if you really want to enjoy the hobby.