My whole family is from Denmark, and "Virtually no crime, no poverty, no trash, almost everyone is middle class", isn't true even there. If there was anywhere it ever was true it's Scandinavia, but it's still a stretch when Denmark was only Danes. At least it was much more true forty years ago than it is today. Now there are tenements and slums (government subsidized) in my hometown of Arhus every bit as bad as Darst/Webbe was here. No one goes there, including the police unless they have to. The Europe you're talking about is fading fast because the population of native Europeans is shrinking.
Socialism can work rather well when everyone shares the same language, culture, heritage, morals, values, goals, and beliefs. Once you introduce "diversity" into that delicate, cultural formula of one-size-fits-all it falls apart very rapidly, as it is doing before our very eyes in Europe.
I would rather drive through the worst parts of East St. Louis at night than certain suburbs of both Western and Eastern European cities. There, as here, it has everything to do with culture. Significant parts of Europe are simply no longer European. Even 20 years ago Amsterdam was, as you say, spotless. Now I continue to be shocked every year I go at the amount of trash and litter everywhere. They do a pretty good job of picking it up, but it reappears every morning by the ton, and it never used to be that way. I'm over there all the time, and it is changing fast.
It worked for them when they didn't have to protect themselves, and they were all the same. Enjoy what remains while you can, because it's all going to be gone very soon.