This may come as a shock but most people want to do a good job, even if they work for Citi or Delta or Comcast or where ever.

Okay, maybe not Comcast.

I never said the contrary. But a tons of these systems are old, and people knowing how they work are long gone.

Plus doing a proper post mortem and understanding how it works woudl take a lot of time and money. Things they most of the time to not have budget for.