[opportune]

I think there are a few different but related concepts bundled in “law enforcement” here.

A low-trust authoritarian state that restricts personal freedoms has to use heavy handed policing/secret policing with severe punishments to maintain that system. Without heavy policing the state would probably collapse internally.

A regular place needs policing to prevent the kinds of crimes we consider unambiguously bad like murder, theft, rape. Like I mentioned elsewhere trust/cooperation is game theoretical, and I think that shows up in our genes such that there are always some latent number of people predisposed to antisocial behavior. So you always need that.

But in the second case, the level of trust does reflect how much policing you need. If there is not much crime you don’t need that many police. You probably do always need some but the real world demonstrates that some places just have more criminality (low trust) and require more police.