GitLab is just as bad, just not as big so doesn't get the coverage. https://status.gitlab.com/pages/history/5b36dc6502d06804c083...
And of course many people self-host which changes a lot of the equation (which you can also do with GitHub, but not for free - and FWIW our self-hosted premium gitlab has about an hour a day downtime, which we've been told by the team responsible is an unavoidable side-effect of backing up gitlab).