Not sure what it's like in the SV but here in the midwest I know a lot of people are hired through third party recruiters, and even a small team can place hundreds of candidates per year.
EDIT: Sorry for the confusion, in this case I have no idea why the recruiter revealed the "true $ amount" to me, rather than just the amount I would make.
They wouldn't be taking the $30/hour from me, they'd be charging the company I'd work for obviously.
99% of the time you only see the amount after the agency takes their cut.