There are too many cars in San Francisco . (there is not written double) There are many Chinese tourists in New York. There are a lot of corn in Mexico. (not double, and there is a lot of corn...) Here are too many people in Beijing. You would say: Here in Beijing, there are too many people, or: There are too many people in Beijing. Here there is a beautiful tower in Shanghai. > There is a beautiful tower (here) in Shanghai Here there are many cherry blossoms in Japan. >There are many cherry blossoms (here) in Japan. "There are..."/ "there is...." is a standing expression (there exists...), not to be confused with "There is the man whom I was telling you about" (pointing at the man) When speaking, there would be an emphasis on "are/is" in the first example and "there" in the second one

It is a somewhat colloquial form which has become generally acceptable and as already mentioned it lends emphasis.