I think this is a very good question, worthy of discussion. I believe the main reason is that the establishment of the U.S. Government held strongly to a princ

I think this is a very good question, worthy of discussion. I believe the main reason is that the establishment of the U.S. Government held strongly to a principle of Checks and Balances, which trickled down to local governments. We have police and we have police of police (so to speak). Of course nothing is perfect, and lately it seems like things may not be working quite as well as they had. e.g. Cops have gotten very trigger happy and no one has called them on it; plea deals have become the norm in court; and unwarranted wiretapping has grown to scary levels.