I think part of the problem is that there's a lot of actors in law enforcement for which "reasonably suspected" isn't important; "can we make it stick" is. Past that, they don't even bother to consider if it might be the wrong person.

There's a LOT of good cops, lawyers, judges, etc. However, the bad ones can have such devastating effects on their victims, that all of them need to be watched (controlled? not sure what the right word is here) more than would be necessary for other areas.