The one thing that surprises me is that many are underage. I’ve never done polling on the topic, but I would have expected ages 18-21 to be in highest demand. I would also expect both customers and the places where the girls work to completely avoid children under 18, if for no other reason due to the higher legal penalties. Perhaps I’m overoptimistic or overly law-abiding.
Younger girls are easier to acquire and control.
Hookers generally start hooking in the 15-21 range, but are careful to tell their clients they’re 18+ if younger than 18. Prostitution is a pretty minor crime but underage prostitution is a major felony so there isn’t a lot of clientele for it outside the super rich and the drug alded poor.