The simple answer I didn't give: No children today are anywhere near freed of the sexual hang-ups and inhibitions that are part of our society, so we wouldn't expect to see an interest in prostitution with children we know and I certainly didn't. The hunch is not based on direct observation of children in those circumstances, but based on a knowledge of children and what would happen in an environment no child has been in so far.

Oh but we do know! The Children of God children were raised in a sexually very open culture. And yet they did not choose prostitution.

I know you will come back with Flirty Fishing, but it is very debatable to describe that as prostitution and certainly does not fit your model of she would rather not do it but for a price she likes she will do it.