I think that history bears that out. Big cities have always felt a need to have legal systems and stout police forces, for pretty much as long as there have been cities, since the times of the Sumerians.
As you suggest, compare that to conditions in small villages and tribal bands, which are typically kind of self-policing. As far as individuals go, there's a lot more social-pressure and a lot less social-anonymity in smaller more tightly-knit groups. In small towns, everyone knows all about who you are and what you're doing.
People are generally a lot better behaved in small towns, but they also encounter fewer opportunities to be creative, unconventional and to chart their own course. That's why twenty-somethings tend to gravitate towards the bright-lights of central-cities, while established older couples with children tend to flow outwards.