It is because you're not using the default httpd.
If you need
to use your custom httpd, install setroubleshoot, start setroubleshootd, and then after an SELinux denial, either run the SELinux Troubleshooter from the menu, if you have gnome installed you can click the start that shows up in the system tray, or else run
that will tell you why SELinux is stopping, what it is stopping, and hopefully how to work around it.
If you don't have any GUI installed, the following command will generate an HTML file you can view with any standard browser like lynx:
sealert -H -a /var/log/audit/audit.log > selinux.html