Most books on system administration do little to cover the philosophy behind the job. However, the following books do have sections that give a bit more depth to the issues that were discussed here:
The Reference Guide; Red Hat, Inc -- Provides an overview of locations of key system files, user and group settings, and PAM configuration.
The Security Guide; Red Hat, Inc -- Contains a comprehensive discussion of many security-related issues for Red Hat Enterprise Linux system administrators.
The System Administrators Guide; Red Hat, Inc -- Includes chapters on managing users and groups, automating tasks, and managing log files.
Linux Administration Handbook by Evi Nemeth, Garth Snyder, and Trent R. Hein; Prentice Hall -- Provides a good section on the policies and politics side of system administration, including several "what-if" discussions concerning ethics.
Linux System Administration: A User's Guide by Marcel Gagne; Addison Wesley Professional -- Contains a good chapter on automating various tasks.
Solaris System Management by John Philcox; New Riders Publishing -- Although not specifically written for Red Hat Enterprise Linux (or even Linux in general), and using the term "system manager" instead of "system administrator," this book provides a 70-page overview of the many roles that system administrators play in a typical organization.