Freakanomics had a really great explanation. Recruiters are paid a percent. The most important thing for them is a sale. Not the amount of sale. So for example

Freakanomics had a really great explanation. Recruiters are paid a percent. The most important thing for them is a sale. Not the amount of sale. So for example would they spend extra time getting you 5k more a year or 10k more? No. If they know you'll accept a lower number their goal is to keep working with the employer. What is better? 20k payout? Or 20.5k payout? Practically no difference. To you an extra 10 or 20 grand a year is huge. To them it's nothing. They care more about the deal happening than optimizing it.