Because people lack faith in God, they are afraid of poverty and they simply don't believe that God is the only one who'd provide for them, therefore they would go into prostitution. just a bunch of lost sheeps if you ask me.
Come on, are you serious right now? don't you think that woman could do that because she has no choice? Imagine the 30 year divorced woman, that lives in a small town with 2 or 3 children. She has no education because she got married when she was 18 years old. Now she is alone. Husband does not help, he does not care about children. What is she supposed to do? Just imagine she has to feed and raise three children alone. Do you really think that she can earn enough money at the "simple" work like waitress?