Spent 6 months at Ohio State as exchange student and I loved it and hated it.
I remember once being asked how was I and me answering honestly, just for an american friend to reprimend me on actually answering.
I was like, "why the hell you asking how am I if you don't care?".
Got to admit though no place is easier to make friends than US. This excess talking can often lay fertile ground to deeper connection that is harder to find elsewhere.
It took us about 2 years to really learn how to talk to each other.
There are other times which are the opposite. Like, when I ask my wife if she wants some rice or some porridge, and she says very imperatively. "I will do it myself." She actually means straightforwardly, I am going to do it myself, not that she's displeased with me and that she's not going to accept any token from me and is going to punish me in several small ways now. (Which is what many of my ex-girlfriends would have meant.)
It's actually hard to give examples in a text medium like this, because so much of it is really context and tone of voice.
That's an odd way to say what you're saying
From GP's text I assumed she's not Chinese but for whatever reason (parents worked there, she was adopted as a grown-ish kid, something else) she spent most of her formative years there.
Maybe we're both wrong but on its face what GP wrote doesn't strike as odd at all to me.
All of my life I've felt at a distance from others who exhibit typical American social habits, and have actually got along better with people from various other cultures such as eastern Europe. (There are a lot of first and second generation immigrants from eastern Europe where I live in the US.)
I have always been perceived as rude and blunt, and in recent years those with typically American social attitudes have even begun pathologizing behaviors like mine as being "on the spectrum".
As to why I am like this was a mystery to me in childhood. I acted just like my family and extended did! Everything was normal at home, and then I would treat someone at school like I would treat a sibling and it would result in arched eyebrows.
Turns out my family's attitudes towards socializing were strongly influenced by my mother, since she was a stay at home parent. And she came from a part of the US made up of small agricultural communities that were mostly German and Dutch in origin. These small communities had transplanted their national cultures in little bubbles all over the US, and by dint of mostly isolation from the broader culture had maintained those mores for centuries.
It was only when my mother had moved away to the city that this culture shock occurred, about 150 years after immigration.
So yes, there is a lot of cultural variation in the US, probably not as much as in Europe, but it exists. There are subcultures within the US of various vintages that exist alongside the mainstream culture that have all learned how to be different and coexist at the same time.
Decades later, that's clearly an exaggeration or just plain wrong, but it is certainly true that people do underestimate cultural differences within the US, and overestimate them within Europe.
The language barriers makes Europe much more culturally diverse, but also makes that diversity much harder to discover since you can't fully understand a culture without learning its language.
It is more like the cultural difference between Canada and Mexico, you don't have such a wide spread within USA. You have some parts that is more like Canadians, and some parts more like Mexicans, but Mexico to Canada is still a bigger cultural leap than anything within USA.
The opposite is true in the USA: nearly everyone speaking English to each other, watching the same TV shows, driving the same cars, eating the same breakfast cereals - easy to believe they must all be culturally very similar, when in fact they are not.
But we also know that there are much bigger differences if you cross many national borders and language barriers by going to the other side of Europe, they too will have those micro differences but when going there you also get many major macro differences.
Because indeed, the American academic culture is full of BS (perhaps the most glaring example being that the cornerstore of hiring is the recommendation letter, which to me is essentially overt nepotism - and in a recommendation letter, every candidate is the best ever, Gauss incarnate, the Chosen One to break the frontiers of knowledge, because if you say even the slightest bad or ambiguous think they're not going to get hired. But everything is like that).
The thing is that in academia everything is competitive (grants, conference acceptances, etc.) so we Europeans must be Americans as well if we want to be successful, because it's hard for a paper, proposal, etc. to get chosen if you're being realistic while some of your rivals are exaggerating everything. This is something I realized when I worked in the UK (not America, of course, but more "American" than the rest of Europe) and then even more when I worked with actual Americans, and I consider this realization to have boosted my career considerably.
On my side, I wanted to slap those people calling others they barely knew "friends", overselling their lunch as "amazing", assuring an outcome with certainty, virtue signaling or refusing to say when something was completely wrong. It's like they were always in a tiny marketing process.
Eventually, I learned to smooth communication, and to appreciate their enthusiasm.
But it did take time.
Also I must confess I have an American filter permanently on, now. If something comes from the US, I just assume most of it is BS until proven otherwise.