I addressed this in my previous response. It is still an external trust, even if you have redundancy.
> - You need diverse Operating Systems and Databases.
I have never ever seen a company run the same server side software deployed to multiple different operating systems.
> - You deploy in phases with canary releases.
As I mentioned in a previous post, there are going to be critical enough systems that may be under a serious threat of breach that any wait is not worth the risk.
Also as I have already mentioned, in many cases automatic updates is turned on for compliance reasons that may not allow what we think is common sense for the vast majority of software.
> - You don't deploy on Fridays....
I agree but to the best of my knowledge this was essentially a security definition updates not a code update. That is the kind of thing that you would push out when you have it otherwise your systems could be vulnerable over the weekend.