Life is full of situations where no one acted unreasonably but something undesirable still happened. It's especially common for no one to see a potential problem, and thus for no one to be assigned the responsibility of dealing with that problem. If you have any stake in the overall success of the team, it doesn't matter whose fault something is, you just want the problem fixed.

Yes, 100%. In the parent's example the system should be fixed so that no one can push directly to prod. Failing that, some sort of standardized checklist/process should be put in place. That's true regardless of who personally pushed something they shouldn't, and would be true even if no one ever made that "mistake."