Great stories. I really enjoy reading them and the insights gained from them. That QLD Korean girl must've been one hell of a root!
I reckon the question about why they do this work is pretty much answered, of course it is for the money. The rate we pay to be with them is high compared to other things like getting a legit massage or going to the GP, for a good reason: to enable the high pay these girls can get doing this work as an incentive. The tougher a job is, the higher the incentive has to be. It's as simple as that.
I still think, though, that the "deciding factor" of whether or not a girl will decide to do this for the money is courage. I mean, sure a girl might not be able to afford luxuries, or might not be able to help pay off family debt, etc. If they do not have the courage to do this work, they will just either go without, think of another way to solve the problem, or just put their hand up in defeat.
Courage determines whether or not a girl was a "go-getter" or someone who will just accept what life throws their way.