RHEL and CentOS 7 had updates for all of Spectre, Meltdown and Foreshadow on the day of unembargo-ing.
What can be confusing about CentOS/RHEL is that many shops using them are on a release that came out years ago. But that's an issue because Red Hat supports 10 year lifecycles for their releases, and will go on supporting them indefinitely if you pay them enough. All the software bundled gets feature and security updates through it's lifecycle, just without changing any interfaces, ABIs, or version numbers. This is great for shops that aren't looking to operate on the bleeding edge and have expensive COTS or bespoke software stacks sitting on top.
Of course, you still have to patch, and organizations can't be forced to do that. Hopefully what you were encountering was just the former and not the latter at those organizations.
This allows you to have a stable "base" with unchanging software requirements, configuration and features to work on for extended periods while also staying very secure, which is why it's favored by enterprises. You can find more information on this on their Life Cycle documentation.[1]
This behavior actually extends to the kernel itself, which is likely why the Debian developer is quotes talking about "the majority of the world runs Debian or they run their own kernel", as Redhat, Fedora, Ubuntu, etc run custom kernels that they've patched. You can see this in different bugfixes for a package, and how they have the same version number for the software, but different release numbers, which come after the version in the filename.[2][3]
There are some more nuances to this model, where you can actually get newer software versions at select points, or where they will actually backport new features and not just bugfixes, but those are somewhat separate, and happen much less frequently (point releases in RHEL terminology).
1: https://access.redhat.com/support/policy/updates/errata/