Incidents such as these are rarely a people failure and nearly always a process failure. People will always make mistakes — perhaps seniors will make fewer mistakes than juniors, but no-one makes no mistakes.
A: I'd like to hire some people to improve our processes. It will take time and money and prevent future problems, but you will never notice.
B: Time and money and no new features? No way, I won't approve that.
A: tries to sell it some more even though they are technical and not a salesperson
B: No.