It's hard to be hungry. It's hard not to have a nice place to live in. You feel real desperate. Poverty is very punishing. But poverty isn't enough, because poverty alone does not provide a pool of women for men to fuck on demand.
Poverty is insufficient to create that pool of women, no matter how hungry women get.
The assumption may be wrong. The assumption does not create the pool of women who are prostituted. It takes more than that. Incest is boot camp. Incest is where you send the girl to learn how to do it.