You said "developed/deployed" as if it were the same thing. Even if you somehow checked in the giant flaw, bypassing all code review and automated testing, it'

You said "developed/deployed" as if it were the same thing. Even if you somehow checked in the giant flaw, bypassing all code review and automated testing, it's not like that would suddenly appear in production. Google isn't some PHP hack where you just copy a tarball to The Server. Binaries of even slightly important systems typically go through many stages of deployment, first into unimportant test systems, then usually very, very slowly into production with lots of instrumentation and of course, quick and easy methods of rolling back to the previous release.