Setting aside the greater civil rights and liability issues for a moment.
The problem as I see it is that I'm not sure anybody really knows how to train an LEO to deal with 20 meth-heads, belligerent alcoholics, or worse, the criminal low-life subset who doesn't need any chemicals to be violent, has warrants, a couple of phony ID's and a good story, and then "freak out" when the cuffs go on. And after days or weeks of that, THEN the officer has to correctly read the "IFF transponder" on a freaked-out housewife/"good person" who's just having a really bad day and made an honest mistake with her dead sister's ID.
And, after enough of it, you're made to feel that if you give too many people the benefit of the doubt, one day, the meth-head will stick a butcher knife in you, or the crack whore's "baby daddy" who's got warrants and parole violations a mile long, standing in the closet and "Ain't goin back, no way no how", unloads on you with the sawed-off 12ga right through the door.
And that's just the arresting/responding officer.
Then those staffing the intake center have none of the context that the innocent person was arrested in. And they have almost no contact with the law-abiding public within the context of their job.
None of this absolves the department or any individual of civil or criminal liability for what happened. When the speed limit changes from 55 to 25, and we don't see the sign, we don't get out of the ticket. When this happens to an innocent/good person, and they couldn't tell, I don't think that the officers or the LEA are off the hook either. "Ignorance of the law or the circumstances" cuts both ways, IMO.
However, I know it's a job I could not do, much less do better. I'd either be the "trusting rookie" who winds up dead or maimed at the hands of some junkie or career criminal, because I "missed the signs", or if I survived, I'd be a disillusioned veteran who may well have done as those officers did.