I've hired tons of people, I've never offered someone less because they came in via a recruiter. You typically budget for salary + recruiter fee and if someone is hired organically then that's a bonus.

You don't pay someone less because they came via a recruiter because then they are going to be poached for being underpaid. You also don't pay someone more because they didn't come in via a recruiter otherwise now I have guys working on varying salaries which creates issues if that comes out in a team.

source: prior founder, hiring manager at large companies, etc