Honestly: I've thought about this a lot for my thesis and the optimal policy isn't super clear to me. Everything is a tradeoff between the extensive and intensive margins. I don't want to talk about this in detail given twitter's Mood today, but I think it is a nice study . . . https://twitter.com/k1ug3/status/1013799233483182080 …
This gets really really really challenging with underage sex workers, for reasons I bet you can imagine. This is a nice ethnographic-ish study of street youth in New York, you can get a handle on some of the trade-offs involved. It's a mess. https://www.urban.org/sites/default/files/publication/42186/2000119-Surviving-the-Streets-of-New-York.pdf …