The following passage reminds me of Steven Pinker’s The Better Angels of Our Nature,
Today police are invariably linked to violent crime, but their history would suggest otherwise. England, in the thirteenth century, was a rather violent country: the homicide rate was 18–23 per 100,000 population, and violent deaths accounted for 18.2 percent of all criminal indictments. However, the trend in violence from this period until World War I was steadily downward. By the seventeenth century, homicide rates had fallen by half, and the fall continued throughout the eighteenth century. By 1890, “only three people in all of England and Wales were sentenced to death for murder committed with a revolver.” All of this was done in the context of private provision of police and justice. It was not until the nineteenth century that policing in England became publicly provided. The steady decline in violent offenses from the Middle Ages on is evidence that the emergence of the public police in the first half the nineteenth century was not in response to a sudden increase, or continuing high levels, in violent crime.
— Douglas Allen, The Institutional Revolution (Chicago: University of Chicago Press, 2012).
Allen makes a convincing case that it was product standardization that made public policing relevant. During the late 17th century and throughout the 1800s, new technologies made capable the production of non-variable output, because methods of production became more precise. Previously, output was largely artisan in nature, and the final product was variable (different units of output varied in quality and characteristics). In the case of theft, private justice was relatively efficient, because it was easier to link product with owner. Related, the lack of a public road system made it less likely that stolen wares would be taken to distant markets. However, standardization made it more difficult to know who owns what and a well-maintained public road system arose, with consequent long-distance markets, made private justice less effective, leading to the establishment of a public police force.