To steelman this: I've never worked at any of the companies you listed but most likely Red Hat and IBM employees (Is there still a difference?) are being paid specifically to work on Openstack, as they get money from support contracts. When Walmart of Chase use Openstack there is a rather small team who is implementing openstack to be used as a platform. They are then paying IBM/Redhat for that support. There probably isn't really the expertise in the Openstack team at Warlmart to be adding patches. Some companies spend a different amount of money on in house technology than others, and then open source it.