There is a big difference between forced prostitution and working girls that sell themselves by their choice. Yes... there is human trafficking. Yes... there is sexual slavery. But, not all sex industry workers are forced or trafficked or slaves.
True. There are reasons that women (and men) turn to this business, but it's certainly not forced.
Sadly, a number of DH girls are usually in debt or have sick family to support. (or husbands that can't/won't work... etc.)
I know of a few specific stories where women are working to support their kids' schooling costs (college, high school... etc.)
Others have families that don't know what they do for a living, they only see the money coming in... and in some cases the family does know what she's doing secretly but doesn't let on about it since there is money coming in.
Other girls out there are hoping to hit the jackpot with a sugar daddy (and some do) or someone to marry and retire out of the business with their every need taken care of by some new rich husband, etc.
Look at those high school girls that have been caught in the news recently, on going on dates for money (no idea if any 'favors' are exchanged or not) or getting gifts in return. Nobody is forcing them to do this, they want the extra money and attention that they can't get from their family. fact.
The real problem in Japan isn't the 'regular' fuzoku services, but those underground markets where children are exploited. This apparently is coming more into the public eye with the changes in Japan's possession laws. Let's also add that there is probably a larger hand at work when it comes to Korean and Chinese girls working here, probably some filipino too.. there are stories of girls coming to Japan to work here temporarily but only to be held hostage with their passport taken from them. (This is trafficking and of course, slavery.)
Outside of Japan, other parts of Asia have serious problems... which have been well covered by other media outlets.