It is true. When a policeman breaks the law himself he might get covered by his higher ups and merely lose his rank or the job but still not face any criminal consequences.
It depends on how corrupt the local establishment is. The cops play a tactical role.
For reference, see the original handling of the Jussie Smollett case. Clearly laws were broken, but corrupt higher-ups provided cover.
Of course not.
It only means that your DA is a dirtbag, and your cop is a dirtbag. (It's also likely that the dirtbaggery extends to others in city leadership. The judges, the mayor, some council people. Etc. Just like the dirtbaggery in the police force likely extends to other cops in that department.)