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?
I agree with you, and that would be the case IF she ever got a job as a waitress or anything like that, usually when you have kids you can't get any jobs, people don't want to hire you since you are a liability. I went through something like your describe. I was 30, divorced and with no education, I had an 8-year-old and no one would give me a job. I'm not a prostitute though hehehehe

because I had my parents support, but I had to move back to their house and become a "child" again under their roof under their rules, so I know the desperation you might feel where you just can't find any solution for a situation like this.
On the other hand I believe there are women that choose this path because they can become really wealthy, and they have a talent for it.
I don't know if being a sexed up person has any influence in it. I imagine it does, if you like your job you'll do it well and customers will be back and ask for more, like in any other job, so one of my deepest secrets is that I think I would be a good prostitute! LOL