Throughout most of human history “standing armies”
Countries didn't need standing armies until they came up against countries with standing armies. Rome is the best example I can think of. If your society is instantly subjugated by another country it doesn't work in practice.
Police
US Wild West was like that. I was called the wild west because many successfully raped and killed their way across the country without ever being caught because of uncoordinated community response. There was also slavery supported by local communities so no one local was going to change it.
Expecting people to be generally good in the absence of enforced regulation through the state's monopoly on violence is the same claim libertarians make.