Please keep in mind that this is not true worldwide. In various countries you're only admitted after 1.5-2 years of police-specific education. You might still not be a police officer if they seem you unfit.
Also, you don't seem to value plumbers or construction workers. A colleague used to be a construction worker. It's very interesting to hear the knowledge he has on that. Plus pretty damn handy for understanding how to improve your house. Just because he did a lot of work with his hands doesn't mean he isn't damn bright.
> Please keep in mind that this is not true worldwide
You're correct and my comment is US centric. What I find interesting is that some US cities have seemingly moved farther from a more educated police force, removing requirements around having college degrees and reducing trainings.
The moment you understand that, it's not a mystery that they sort of blindly accept tools that seem to work without deep introspection. They are not equipped to be a data analytics shop, they are equipped to fill out paperwork and sometimes get into tussles.