I have a pet theory on this that is entirely based on my own biased views: societies which are communal, whether around a family, village, tribe, etc..., tend to keep sociopathic tendencies in check. Either the sociopathic individual is exiled from the group, or at least identified and prevented from harming the collective. If the larger structure is still made up of smaller (at most 100s of individuals) communities, exiles risk becoming pariahs and without any societal support, it becomes next to impossible to strive (or even survive).

In highly individualistic societies, a lot of the most personal checks and balances are removed. You no longer have a tight-knit family that imposes some moral framework and behavior on it's members (good or bad).

Having said that, I'm not sure whether there are any truly communal societies left in the modern world. I suppose some isolated, rural communities could qualify, but pretty much all modern countries are now individualistic. Family values are slightly more pronounced in the East/far-East, but not to a degree that matters. Being successful still often trumps being a decent human being.

Indeed! The ability to make a mess then move on to a new crowd to abuse/scam/etc. without your reputation fully following you, is hugely enabling for sociopaths.