I have friends of sicilian origins and this will probably be wrong to their land. Mafia-driven blocks are dangerous, yes, but not for robbery or the like. More because one could take a bullet NOT aimed to him. The closest thing one could say about those places is that there's a civil war running.
Also, all kind of criminal cartels exists, not only in the south and not only the world-known "mafia". Northern ones are simply more shadowly driven, with more enphasis on corruption.
I disagree that the problem of america, US in particular, is about the time they were inhabited [by westerns, at least] and thus "build less stuff" because it take a lot of turns and hammers

. Tocqueville in 1800's wrote about a whole culture of small, wooden, white-washed ghost towns. My opinion is that the US where - are - a young civilization with strong migration component. Only well radicated cultures usually build something "that last". On the other side, this sometimes make US culture more vibrant [vain, an european might say].
If you look on central-south america, that usually received migrants only from a few selected places, culture is somewhat "older" and radicated. That's even slightly true for the southern part of the US.
US citizen are used to a different concept of space, time and travel compared to those of europeans. As you might know, in Europe is VERY STRANGE to get a work in a city more far than, say, a hundred kilometers than the one you were born. And in those couple of Kms a LOT will change. To have the same effect in the US one need to travel much more.
Luckly, in Europe people started migrating up and down again, which is good to counter stagnation.
Another minor thing that make
me think about causes is religion and concept of state. First, protestantism [all form of it] is more work-driven than catolicism. This increase wealth and industrialization but decrease art, usually. Art, in any form, is for people that like to waste their time and money. Lazy people: art cost time and resources but produces nothing tangible. This goes not well with a religion that say that you must be dutyful and just and restrain yourself. And no, I don't know a single catholic that
really belives in that.
On the other hand, US are born out of a culture much more democratic that the european one [I'm not speaking of actual years, so political debate about the "right now" it's irrelevant]. Again, democracy have little time to waste, because it takes already a LOT of energy to drive a proper one. Usually art is for a few, rich, bored people which want to prove they are better than the ones they feel as lesser. That include other rich people and end in a race to the most luxurious/mecenatic one.
On the language discussion:
Italian is an artificial language and a young one. Remember that it is born from a few [thousand

] intellectuals that built it from scratch for litterary pourpose. Then it became a national language because one couldn't understand another if he was born more than a hundred km away. Literaly, you will not understand a single word. I'm from piedmont [NW Italy] and there are more chanches that a french will understand my dialect than a venetian [NE], or latian [centre]. Then again I sometimes understand souther dialects [spare words] because of the french influence on their culture.
Sources from our language changes from latin to french, to deutch, to spanish and in the late years from english. A more deep example: french people uses their own therm for every single new concept [and could be very irrational with it]. Italians will use the foreign one and be fine with that [remind, we DO NOT have a strong sense of nation, as a nation

].
This make the roots of our words a mess.
As a rule of thumb, latin is the basic for grammar. Italian is a latin language similar to spanish, french, romanian [I never really undestrood HOW they managed to keep the latin intact in a slavic millennia. Probably low profile domination? No domination at all?]. Many words from those languages are interchangable at some point. Italians, kidding, say that they could speak spanish simply putting a "s" at the end of every word.
Yet, there are differences: spanish is influenced by moorish and goth domination. French is born from a totally different path from the mediterranean "offsprings", the langue d'oil, and out of Frank's.
This cause a lot of trouble with some words, but it's a lot easier than with anglosaxon languages. I think I've deleted a couple of words in this message because they were NOT what I was thinking they meant

Could only guess about the ones I have missed.
And then one discover celtic languages and goes all like "where are gone all the vocals?". They probably changed them with a bunch of Ls.