From my experience, the key point in this story is that if you bother people enough with useless manual interventions, they will come up with a way to automate themselves out of the job.
Furthermore, the solution is often simpler and cheaper than the monitoring infrastructure.
And, well, the rest of the anecdote is based on the waste of money caused by the fact that the external company had everything to gain from overengeneering the solution.
The engineering team could adjust the scales to automatically tip an empty box off the line, recording when it was found. Win (data to identify the source of the problem)- win (line guy doesn't have to walk over) - win (no empty boxes shipped)!
The box-filling machine was not working properly. This could be due to wear, poor quality boxes, a problem upstream with where the tubes came from.
Although a solution was found to the problem of shipping empty boxes, the process in the factory was not resolved in that the source of the problem was not identified.
The new scales made it possible to find the empty boxes and pause the conveyor belt so that the offending light box could be removed.
However, the operator went ahead and did his own thing with the fan, not asking for authorisation from the site electrician, his line manager, senior management or anyone else. Because of what he did it no longer became possible to have the line stop as soon as a problem was detected. Or to have the scales machine do the accounting for this. This information may be important for the engineering department to know they have to clean/fix/replace parts on the box filling machine.
If it was my factory I might not have sacked the operator for being a 'loose cannon' however I would not have rewarded him for his ingenuity. To be fair he did not know of the empty box problem until the scales came along, he was not 'wilfully ignorant' of the problem because he did not know about it. However, his fix did not solve the core problem and it only made it harder for the engineering team to remedy the situation. (The engineering team were not wilfully ignorant either).
So this is a silly story that might be a funny anecdote at an after dinner talk but it has no relevance to a real factory and the processes involved. If anything it tells a different story of how out of touch we are with manufacturing.