Companies hire their own auditors. No audit partner wants to have to go find new clients, so they bend over backwards to appease the existing one. The partners do the math of “I’d rather have a 1% chance of my client blowing up than a 50% chance of having to find replacement revenue is a zero sum game”

Unfortunately, what’s rational for individual audit partners isn’t rational for the firm as a whole. And this is why Enron/Anderson happened. And Wirecard.