There definitely are, but they don't sell them on the street. Underage street prostitutes do exist but they're mostly runaways not kidnapping victims. I remember there's a really good article about it from a few years back by an anthropologist who studied the problem. Edit: [Found it](https://www.miaminewtimes.com/news/lost-boys-new-child-sex-trafficking-research-demolishes-the-stereotype-of-the-underage-sex-worker-6385037). That took a lot of digging, it's been scrubbed from a bunch of places.