That's because "The ringleaders, Isaias Flores-Mendez, who is about 42, and his brother, Bonifacio, 35," are both " natives of Mexico", as the NYT puts it. I. E. they're immigrants, too.
I'm pretty sure all of the "More than a dozen members of an alleged international sex trafficking ring " who Homeland Security Investigations arrested were natives of Mexico. Most of them are, like their "trafficked" victims, illegal immigrants. A couple were charged with " illegal reentry after deportation."
This all very bad:
The victims are often beaten, threatened with physical harm to them and their family members, sexually assaulted, and verbally abused. In a typical day, a Mexican sex trafficking victim in New York has sexual intercourse with 20 to 30 customers. Each customer usually pays $30-$35 for 15 minutes of sex. [HSI special agents arrest 13 in connection with an alleged international sex trafficking and prostitution network, May 1, 2013]"Mexican sex trafficking victim" could mean either "Mexican victim of sex trafficking" or "victim of Mexican sex trafficking". Actually, it's both. And the customers, of course, are also Mexicans, frequently illegals.
Do they know or care about the conditions that the women suffer? The whole thing is enough to make you think that mass Mexican immigration is a bad idea.