Given the net result is pushing sex work into illegal spaces, thereby making trafficking and other exploitation harder to report, I'd say that the most likely a

Given the net result is pushing sex work into illegal spaces, thereby making trafficking and other exploitation harder to report, I'd say that the most likely actual reasons behind said official statements are (a) moral puritanism of various forms (b) hidden commercial interests. As to how much of which, stuffed if I know (and even ignoring real estate, the funding and attention given to 'rescue organisations' as part of soi-disant anti-trafficking efforts probably gives them at least an incentive under both a and b). Though "pressure from an increasing level of (a) at The Hague" also seems plausible. (tl;dr - I dunno exactly, I doubt there's a conspiracy as such, but I also don't believe the official reasons are even close to the whole story)