From what I've heard from low-level employees, HR was basically entirely automated some years ago and the HR staff existed as a kind of helpdesk to solve exceptions. A simple example I heard is that employees are automatically fired after 3 days of unexcused absences, but occasionally an employee's doctor's note somehow doesn't excuse their absences, so they get an e-mail saying they are fired, call a phone number in the footer of the e-mail to talk to HR and open a ticket, and HR marks their absences as excused and unfires them.