Why do governments need monopolies on force? There are nation states without military forces. Do you know the origin of the Second Amendment for example? The Virginia Declaration of Rights was written way before the US Constitution. Here's a part of it, and it should sound a bit familiar. The Supreme Court cannot twist its meaning so easily as 2A too:
Section 13. That a well-regulated militia, composed of the body of the people, trained to arms, is the proper, natural, and safe defense of a free state; that standing armies, in time of peace, should be avoided as dangerous to liberty; and that in all cases the military should be under strict subordination to, and governed by, the civil power.
In other words, standing armies are dangerous, and they threaten individual liberty. There's no need for them in times of peace. An army should be raised by militia forces too. The Swiss still do this today. Many other countries rely on militia forces as well.
We the People, as in regular people who live in a particular area together, are the best defense force. There's absolutely no good reason to have a centralized outside force that is not under our control.
I'm a private investigator and student of security in general also. You might not know it, but police forces controlled by governments is a relatively new concept. Even in early United States of America history, all police functions were private. Towns would elect sheriffs as we do today, but there were no corporate "agencies" controlled by groups that are not accountable to the people.
Worst of all, those "proper functions" of government as you suggest have a long and constant history of abuse. It never works in other words. Given enough time, such entities always end up consolidating power and abusing it. Oligarchs cannot control decentralized groups of people either. They can easily control the opposite however.
The key is a legal monopoly on the use of force in retaliation. Not to initiate it. The police force is the legal monopoly on retaliatory force, aside from the right of private citizens to use force in self-defense where it is required.
You state that the government shouldn't have that power? So who should? The people? So you want random citizens to have the legal right to use force as they see fit?
I'm against all monopolies. The police do initiate violence all the time. Hell, they murder people. Is this a joke?
All people should have equal protection and rights under the law. There should be no double standards or special protections.
Who is supposed to enforce the law? Without an answer to that, you have no basis for any society.
The fact that SOME policemen initiate force when it isn't called for doesn't mean that the police force is inherently evil. It means our court system needs to be better so that we can effectively prosecute them and ensure they can't break the law again.
The courts and the law are on their side, not ours, so that will never work.
Who is supposed to enforce the law? Is that what they do, ehh? They are mostly revenue collectors, investigators, and warrant servers. There should be no revenue collection, and private companies and individuals provide the other services as they have in the past. Hell, I'm a private investigator, and I own a security business.
There is no good reason to have a police force like we have today. All of its functions would be better served by the private market. Communities would have courts, court appointed judges, etc. Again, as it has been done in the past.
The police force enjoys special protections and huge double standards compared to those who are not police. That is inherently bad for liberty and for those who are not police. We all want to go home safely at the end of the night too.
I've had a badge before too briefly as a county deputy, I have a brother who is a cop, and my wife's best friend's father is a special victims investigator. In other words I'm not writing this as some raging cop hater.
The current system is broken though, and it does not need to be replaced. It needs to be dismantled. Look around you. Almost all humans are peaceful and interact voluntarily. The few that do not would pay a heavy price for it by the communities they victimize too. All of it would be done without a monopoly on force by government police too.
This is not even getting into how police victimize communities, their high rates of spousal abuse, and how sexual predators and other predators gravitate towards the jobs on purpose.