Alternatively, you have staff pointing out a possible flaw. That staff's time was already allocated; their noticing a flaw is a) taking time away from their allocation, and b) tacitly critical of decisions made above their pay grade. And even if they are right, the manager won't get credit for prevention, and in fact will get punished for "wasting" resources in an ad hoc way, rather than what they were acquired for.
It is depressing in the extreme to work for such an organization, and you were right to quit, because over time these perverse incentives will start to shape you whether you like it or not. The very idea of owning your work, of caring about real-world outcomes, becomes anathema as a matter of survival. You have to exist, along with your org, in a checking-the-boxes, don't-notice-what-you-aren't-paid-to-notice, mode. It's safe and comfortable for the body; it is deadly to the soul.