Normalization of deviance doesn't happen through people "making mistakes", at least not in the conventional sense. It's a deliberate choice, usually a response to bad incentives, or sometimes even a reasonable tradeoff.

I mean ultimately establishing a good process requires make good choices and not making bad ones, sure. But the kind of bad decisions that you have to avoid are not really "mistakes" the same way that, like, switching on the wrong generator is a mistake.

Quite, normalization is another failure mode, besides simple mistakes, that process has to account for.