I am both freelancer and Employer on freelancer.com
It's really frustrated to be freelancer on there, because once Employer awarded the project to freelancer, freelancer.com charges fees from both sides. As a freelancer, if employer cancel the project after awarding it. We lost money of the fee that freelancer.com charged. The fee they charge is like 3% to 10%, imagine if you get a 800 USD project and client awarded you then cancel it.
As an employer, I have worked a lot of freelancers on freelancer.com, who do not give good quality of work.(Even they have good rating.) And found few good ones after tried to work with very bad ones, it turns out you pay fees several times for same project, and spent more money then the actual budget because you have to rehire someone when you found out those freelancers were wasting your time after work started and then tell you they cannot complete the work.
I really think if freelancer.com really want to charge that much money, they really should consider doing quality control.