I'm an immigrant from a slavic country. I grew up in the north east of the U.S. -- the more continental/European part of this country. My experience has been that Americans outside of this small cultural nook are: 1. dishonest and insincere; 2. socially performative and inauthentic; 3. conversationally shallow and mentally dull; 4. self-centered and unconscientious; 5. culturally stunted, making for a characteristic mixture that precludes them from having any deep friendships.
I'm sure many slavs will understand the culture shock of being asked an insincere "how are you?" Americans don't care how you are. It's a social performance to signal "I'm normal. Are you normal?" Once that has been broached, the next step is to engage in a shallow, safe, and completely meaningless conversation to assert to one another that yes, each person is still mentally sound (in the American definition of the word; i.e., do you fit in). As opposed to Europeans (sans Nordics), Americans are deathly self-conscious of their image, what people think of them, and whether or not what they say can and will be used against them in a court of public opinion. This ends up manifesting in shallow conversations and a lack of authenticity. Very few Americans will be able to say, honestly and openly, to another what they really think and feel. And what they do say is always chained down by decades of having to self-censor, so it comes out inelegant, clumsy, and as though they never really put much thought into what they think. It is impossible to make friends if you're unwilling to let go, and speak from the soul. Friendship requires vulnerability. It requires that you be able to present yourself as who you are, and be ready for someone to not like you. Europeans can handle disagreement and coexist with one another, despite differing opinions. In spite of America's "melting pot" status, they still cannot coexist with different ideas and view points -- they always take it as a challenge to make their ideas known, rather than to try to understand the other's -- or as a podium to make known how insular and unworldly they are.
Having been in this country for 40 years, I have not made a single American "friend." I have countless American acquaintances in my phone book, but none are what I would call a friend. The only interesting conversations I've had with Americans have been from those on the autistic spectrum, the rest have been utterly uninspiring. Contrast this to my rich social life with the those from all sorts of cultures: latins, europeans, slavics, asians, oceanics, britons, I have numerous people I call friend in these groups. They understand the give-and-take, push-and-pull, speak-and-listen dynamic of socialization. Americans only know "me, me, me." How can you be friends with someone who only ever talks about pedestrian topics? Who never is truly genuine with the world, nor himself? Who is not open to live and suffer? You can't.
American's issues stem from their lack of culture. They are devoid of any deeper concepts or values. Partly the incessant protestant values. Partly that anyone with a soul will have to deaden themselves to get along. Partly the inability to stop what they're doing and simply exist.
Provocative yes. But these are my observations, and they haven't been twisted and turned to comply with whatever flavor of cultural fad pervades the current zeitgeist -- or butchered to "get along."