The recent bestseller Superfreakonomics had a chapter devoted to the economics of prostitution. A very interested read. The authors studied urban streetwalkers (who actually make more money using a pimp than not) and more professional escorts of the type you described. It's crazy how much money these women can make. A half million a year easily --and with little fear of ever getting busted or assaulted.
I often wonder with the throngs of young women lining up to enter the porn industry (because they claim to need the money for college) that they don't just go work as escorts. They can make at least twice as much money having sex and don't ever have to worry about their friends, family, future children, spouses, employers, etc. finding their photos and the 'net. And when they want to quit, they quit and there's no recorded history of them ever being involved in the dirty, shameful business of selling their bodies for sex.
Go figure...
They may imagine its discrete, but these things have a way of getting out. No one wants to marry a hooker.
The porn thing is a head scratcher. Yeah, there seem to be lots of young women willing to do it. At the end of the day, it must be a combination of the $$ and the delusion that they are legitimate actresses or models. It’s a really foolish choice though. I really can’t see how someone can have a normal life and/or career with their sexcapades floating around on the Internet.