That is outside of police renaming prostitution busts as "human trafficking" crackdowns. If you think about the business mechanics of it for just a couple of minutes it makes no sense as an operation, regardless of the morality. The amount of risk and points of critical business failure you take on for probably minimal to negative financial gain is insane. Your main assets, your slave prostitutes, are your biggest and most volatile liability, and your source of income is your second biggest threat.