Everyone gains the security of knowing that their rights to life, liberty, and property are protected. According to Locke, the main purpose of government is to protect those natural rights that the individual cannot effectively protect in a state of nature.
Protection of natural law rights is not exclusive to government. It’s moral for any person to do that, and so by extension, any organization can be delegated the right to do that.
It’s important to understand that the only thing government adds is an exemption from morality - the “right” to do things no individual has a right to do. And what do we call something that no individual has a right to do? We call it wrong, immoral. Remove this license to act immorally, and what’s left is not government.
You do not have to police people personally, but I phrase my questions from that perspective to make clear that if you don’t have a right to do something, government doesn’t either; they are just people, and all people have the same rights. We can have a full-time protection and investigation agency, but they cannot have rights that individuals don’t have; or they are - by definition - an immoral institution.
If a government was funded morally, it would have to be funded voluntarily; as individuals do not have the natural law right to coerce people into giving them money. If was to protect, it could only act in defense of rights, not act as an authority over people; as no individual is an authority over anyone else.
So it could not tax, not draft, not limit movement or benign behavior in public spaces, not make any law which differs from natural law. Would you still call this organization “government” when it does not govern? When it exists only as an extension of individual rights and makes no claim to authority?
Men are not angels, which is precisely why it’s insane to create a seat of immense power, then choose some from among the imperfect throng to sit upon it. All this does is magnify man’s immorality (see all of history). A free society at least keeps the playing field level. Show me Stalin, Hitler, Mao, without governmental authority, and I’ll show you three misguided loudmouths with more bullets in their chests than murders under their belts.