Have you also belonged to a 'patriotic' militia?    The Sovereign Nation showed up in my little town of 10,000 while my wife was a police dispatcher and I can say that the police force was very edgy, the SN folks had already killed at that point.   

There's clearly a lot more power of the side of police, something you have seen for yourself.    They work in cooperation with legal teams and a closed system of review.    I agree that's a danger.  Add in every increasing means of surveillance, military level equipment, and patronizing political support, yea, it could become a serious problem    But that doesn't make every police action abusive.  Not would I trust a private security force, or guns in the hands of untrained and unregulated civilians.   The latest mass murderer was in a quasi police company that offers private armed security - that didn't work well. 
Neighborhood watch- dead teenager.

So if not the police, who/what would you do to improve domestic security?