Dave, I will respond only to the above. You need to read more local US news to understand. The events I am refering to were not isolated but rather generalized in both departments.
Most cops are pretty honest and decent but there is strong temptation and they have a lot of power.
Political protection or simply lack of care by citizens have turned some of them from being the protectors of civilized society to something else. You may know that very serious scandals involving criminal behaviour and murder under cover of official duty are under current investigation in both cities. These are not small time scandals. The Los Angeles one, with which I am most familiar, has resulted in jail terms for many and will result in more. It will probably result in a complete re-organization of the department or its replacement by a merger with the sherriff's department.