My first job was at the anti-fraud department at a telecom company in the early 00s. Our job was basically to determine whether a new landline or mobile contract was fraudulent or not. Some requests would be flagged by an automated piece of software that was basically a black box to most employees, myself included. We would basically look at the documents sent by the clients and, sometimes, ask a few questions via phone.

I was very young at the time, but I remember basically deriving Goodhart's law after a few months in the job. I don't remember clearly most of the things that led me to that conclusion, but I do remember the most extreme: at some point, management started requiring us to block clearly non-fraudulent phones because the directors decided to increase the blocked installations target. It would include even old contracts by good paying customers that happened to be flagged.

I remember trying to talk to people about this, but the idea that trying to reach a target by any means necessary is usually not a good idea was incomprehensible to most people. Years later, I realized that others knew exactly what was going on; they just didn't care, and I was naive for not seeing that.

It was a few years later when I learned about perverse incentives, Goodhart's law, the cobra effect, etc., and it allowed me to have more productive conversations with people about targets and incentives.