The fact that you need to strip all the references to Redhat and recompile all packages from source (aka CentOS) and can't actually just get the install image from Redhat like you can with Ubuntu means they don't give RHEL away for free.
I don't know where you get the idea that you need to compile CentOS from source from? They distribute images that are perfectly equivalent to RedHats images. The resulting installed systems are binary compatible - I suspect it's not a coincidence that the strings "RedHat" and "CentOS" are the same length.
The main selling point of RHEL is the stability and long term support that makes software vendors like Oracle comfortable supporting it as a platform. If you install CentOS you get that, perfectly free and open source. How is that not giving RHEL away for free?
