That's only really in jurisdictions where it's illegal. It just comes with the criminal aspect. In Holland they even have a union called the red thread.
It is also a case in jurisdictions where it is all legal, because to meet demand it becomes then more profitable to bring (illegally) trafficked women to meet it. In particular, netherlands appear to be one of the highest in trafficking inflows [0, Appendix B].
From [0]:
> Our empirical analysis for a cross-section of up to 150 countries shows that the scale effect dominates the substitution effect. On average, countries where prostitution is legal experience larger reported human trafficking inflows.
Even in jurisdictions where it’s legal it’s still filled with exploitation - e.g. soliciting 18 year olds to do various sex work, like pornography, while they may not necessary understand what they are getting into and just chasing money they cannot get elsewhere.
And how it’s correctly stated, trafficking is still a thing.
