While $200K vs $220K means a lot to you over the course of your job, they aren’t going to risk losing a placement arguing for you to get $20K more so their firm can get $44K instead of $40k and the recruiter themselves can get maybe 60% of what the firm gets.
There was a famous similar study published in Freakonomics about real estate agents.
https://freakonomics.com/2008/02/real-estate-agents-revisite...