Our briefings on what to expect, and how a particular country might be different from the "American Median" comes from our in-country teams. I.E. People who were born there and have had to deal with American Companies.
You can certainly have variability around an average, but, it's also certainly the case that average norms for various countries can be (dramatically) different.
And, as one who has travelled quite a bit, I can tell you German Culture and (for instance) Hong Kong Culture, around things like queues/rules, are so different as to make your head spin. The meeting thing in Brazil is really true. And, if you come out to Silicon Valley, 90+% of engineering companies are fine with you wearing a T-Shirt. Strongly suspect that's not the ratio you would see in London. Culture is real.
Except almost no one has any idea what the American median is, or the Brazillian median is. These are large diverse countries with huge internal variation to which you have not been exposed. New York is a lot more like London than Silicon Valley, even though New York and Silicon Valley are part of America and London is part of England. Even within New York. there's huge variation that most people are unlikely to have full understanding of. A small design studio in Dumbo, a large financial institution in financial district and an advertising company in Midtown are going to have completely different cultures and norms.
If someone tells you, in our country, people are like this, the chance is that you're being mislead. Lots of people tell me that in their country of origin, there are no gay people or something along those lines. People have a very narrow view of what constitutes their own national culture, largely oriented around their own peculiar and individual experience.
You can certainly have variability around an average, but, it's also certainly the case that average norms for various countries can be (dramatically) different.
And, as one who has travelled quite a bit, I can tell you German Culture and (for instance) Hong Kong Culture, around things like queues/rules, are so different as to make your head spin. The meeting thing in Brazil is really true. And, if you come out to Silicon Valley, 90+% of engineering companies are fine with you wearing a T-Shirt. Strongly suspect that's not the ratio you would see in London. Culture is real.