Making things illegal makes the price a lot higher and that it is only illegal for the buyer turns it into a potential extortion gig so the buyer should really be on their best behavior unless they also plan on murdering the sex worker to avoid extortion. Since the vast majority of people don't plan on killing their sex worker you end up with mostly higher prices and lower risk, especially if you can avoid paying out to gangs, which the girl in the article appears to have accomplished, leading me to believe it's more doable than you imply. Getting paid way more for the same amount of work is obviously beneficial.