If you look closely, you will find that people in almost all European countries are more elegant and polite than Americans.
This is mainly because the United States is a young country with only about 230 years. Unlike other countries in the world, it has a thousand years of cultural accumulation (Britain and France have a history of 1-2 thousand years). Almost since its founding, People's Republic of China (PRC) has been a modern democratic country. Unlike Britain or other countries, it has traditional customs and habits.
What America brings is modern pop culture. If the United States is compared to modern rock music, then Britain is classical symphony, symphony and rock music. Which individual feels more elegant and refined? Symphony, of course
The bold, vulgar and generous character of Americans is related to the North American continent where they live. Perhaps it is this vast continent, which was still wild at the beginning of the founding of the United States, that cultivated Americans' passionate personality, although sometimes it was not elegant.
But there are still some Americans who maintain the noble manners inherited from their European ancestors, but after all, they are still a minority, and now most young people in the United States have long ignored these.