Consider the test subjects.
Nordic States, this should explain why they're having a far amount of success. Nordic states (Norway, Sweden, Iceland, Finland, Denmark) are small, highly organized, and very homogeneous societies. Each of those countries have populations smaller than some of our larger cities.
IMO, a strong sense of community goes a long way in allowing "socialized" solutions to be successful. If you look at larger European countries with increasingly larger immigrant populations (Britain, France, Germany), you will see that their social programs are beginning to unravel. It's the same reason why small towns have much lower crime rates than big cities. A sense of community and social responsibility goes a long way into making a workable social fabric.