Federal, state and local governments have been morphing police departments into ever-more militarized roles. Was walking to the subway after work and saw some police in tacticool gear, wearing helmets with what looked like NVGs on them. Why do they need NVGs? Are they going to be doing night operations or something? What are they patrolling?
That’s another reason police don’t trust the police. Why do they need APCs, or any armored vehicles? If more people carried concealed, police would just take statements from the living, instead of getting into standoffs with hostage-takers.
The riots of the sixties and increasingly militarized organized crime (drug cartels) are some of the reasons given for the militarization of the police since - turning them from members of neighborhoods and communities into pseudo-occupiers for a simplified answer.
The people themselves are no longer trusted to make decisions and take actions against criminals on their own. The left has successfully split the police from the people to the point that today most police consider the people they serve to be 'civilians' as opposed to themselves. 'Us' and 'Them', no longer 'we'.