Why httpd service fails to start by default and doesn't create /run/httpd in RHEL7?

Issue

• httpd service doesn't start by default and doesn't create directory /run/httpd automatically?
• Why do I get an error failed adding user 'apache', exit code: 9 while installing httpd package?
• When server is rebooted, apache fails to start.

• Apache httpd fails to start in RHEL7 with following error messages in the Apache logs:

  [auth_digest:error] [pid 930] (2)No such file or directory: AH01762: Failed to create shared memory segment on file /run/httpd/authdigest_shm.930
  [auth_digest:error] [pid 930] (2)No such file or directory: AH01760: failed to initialize shm - all nonce-count checking, one-time nonces, and MD5-sess algorithm disabled
  [:emerg] [pid 930] AH00020: Configuration Failed, exiting
  

• Both httpd.server and systemd-tmpfiles-setup.server fail on startup and fail to create /run/httpd directory with following errors

      # systemctl list-units --failed
        UNIT                           LOAD   ACTIVE SUB    DESCRIPTION
      ● httpd.service                  loaded failed failed The Apache HTTP Server
      ● systemd-tmpfiles-setup.service loaded failed failed Create Volatile Files and Directories
  
      # systemctl status systemd-tmpfiles-setup.service | grep Unknown
      systemd-tmpfiles[639]: [/etc/tmpfiles.d/httpd.conf:1] Unknown group 'apache'.
      systemd-tmpfiles[639]: [/etc/tmpfiles.d/httpd.conf:2] Unknown user 'apache'.
  
      # systemctl status systemd-tmpfiles-setup.service | grep Unknown
      systemd-tmpfiles[639]: [/etc/tmpfiles.d/httpd.conf:1] Unknown group 'apache'.
      systemd-tmpfiles[639]: [/etc/tmpfiles.d/httpd.conf:2] Unknown user 'apache'.