Why should deploying to production be be prevented by needing to wait for tests that do not apply to that environment, but only to a separate product (GitHub En

Why should deploying to production be be prevented by needing to wait for tests that do not apply to that environment, but only to a separate product (GitHub Enterprise Server)? GitHub takes continuous deployment very seriously, with dozens of deployments every day. My understanding is that they try to avoid having code sitting around only deployed to an internal environment any more than truly necessary. They want to be able to fix code issues discovered in production within a shockingly short time frame if the issue is not complex.