I would like to read your data that backs up your opinions with facts. Is that what happened at a PD you worked at if so let us know. I suspect you are basing your opinions on news events not real life. Or maybe someone you knew may have said some of that, if so, was that based on something from many years ago. Although my daily experience was at 4 PDs in 39 years I worked with and had friends in many others. This is how I would make your statement. Based on real police work in the West.
There are a few bad apples, the majority are good hard working moral people. Circling the wagon to protect others ended years, decades ago. It's not worth oneself to lose a job over other's failures or illegal activities. It's better to report the abuse for your own career, the community and Department.
All major departments have police oversight, many have outside agencies including the DAs office or city/county council to do investigations on their officers. Few officers ever abuse their power, if so, they get fired or other disciplinary actions happen. Action taken depends on totality of the offense. No PD or government (city, county, state or federal) can afford lawsuits generated by such conduct. There needs to be stricter standards in hiring. Not hiring based on race/sex or sexual preferences. High moral standards are most important along with physical abilities.
Impartial oversight must be done by people who know the law and how it's applied. Retired cops or cops from other agencies, criminal and civil lawyers should also be considered. The average citizen doesn't have a real clue about laws or how there applied. Attending some real police training and learning laws should be a must before reviewing incidents about proper police conduct or not. Passing judgement on conduct based on watching the news or reading web stories is far to skewed in one way or another.
I find the leos in my town do not understand the law.
My neighbor constantly trespasses on my property, cutting my bushes, dumping lawn debris. The police refuse to do anything, however consistently make up something I did wrong.
I threw a twig on the property border and was threatened of being arrested for illegal dumping.
Another instance while discussing with leo how the neighbor was dumping on another neighbors property that neighbor stepped out of her home. When I called the neighbor over to discuss, the leo threatened to arrest me for inciting.
The leos from town lied about evidence in court during my trial. It was their evidence and they claimed it wasnt!
The neighbor was having a new roof installed early in morning, in violation of town noise ordinance. The leos tried to convince me that since the roofers were using "lawn tools" to remove shingles, they were not in violation of the ordinance.
I was told by 2 officers that they were "old school and do not have to be nice to people". And one of those officers is a trainer for new recruits.
I had to request a wellness check for a relative. The sheriff office in SC was totally professional and gave me the procedure that I had to follow in initiate the check with the PD in my town. The local dispatcher was rude and refused to follow the steps I was given. When she finally turned it over to an officer, he acknowledged the procedure was correct and initiated my request.
The former chief had all his windows in his car blacked out. He was known to be a drinker and the windows facilitated drinking behind the wheel.
I guess some departments are better than others.