I don't think it's that the police have "issues" per se, but that it is instead the very nature of the beast.

The job of the police is to confirm that you're the guy they're after in order to administer what the authorities consider to be justice. Your job is to not give them that confirmation, especially if you're innocent. If you're guilty, you obviously and already know this, but far too many people who are innocent have no clue.

We have, and have always had, an adversarial judicial system. Most people think it starts in the courtroom, but no, it starts the moment a police officer, investigator, detective, or other officer of the law wants to talk to you.