oDesk supports slavery, they allow publishing of fixed price job for 100 USD per month, 5 hours working per day from Monday to Saturday. screenshot: http://s10.postimg.org/57ya3tga1/odesk2.png
So, if Iran allows selling of kidney for max 5000 USD and user is from Iran, but oDesk is registered in the US, odesk must forbid such business.
It is the same about economic exploitation. Whatever excuses odesk can find, you can see from screenshot that it is typical example of exploitation, published mentioned salary and monthly work 5 hours per day 6 days in a week.
It is not contract for some product, it is monthly salary. One more woman wrote negative experience (race and age discrimination): https://www.change.org/petitions/odesk-corporation-make-the-odesk-marketplace-fair-for-everyone