[CentOS] CentOS 7 AMIs and deletion of root volumes on AWS when terminating instances

Hi,

We have noticed that the CentOS 7 AMIs in AWS do not delete their root 
volumes on termination.  It appears this is the way that the AMIs were 
created.  The AWS Linux AMIs appear to have this enabled.  So they do 
delete their root volumes on termination.

Does anyone know why the CentOS AMIs are created so that they don't 
delete their root volumes on termination?

Herc