Explain the problem of learning a foreign language in America

Problem- One problem for Americans is that they start learning foreign languages after they are adults which are the worst time to start. Children pick up foreign languages very easily and are able to pick up the correct accent as well.

Part 1- This is extremely hard for adults to do. Most Americans do not seriously start to learn a foreign language until they are in college or older.

Part 2- In contrast, in many foreign countries children start learning English in grade schools. Some spend some time as exchange students in U.S. high schools and then continue their studies in college.

Part 3- When Americans get such a late start; it basically means that they will not attain sufficient fluency in some languages to use the foreign language for business.

Part 4- European languages are easy for Americans to learn and it is possible to attain sufficient fluency in Spanish or French, but it is nearly impossible to attain that level of fluency in Japanese, Chinese, Arabic or many other languages unless a person starts very young or lives in the country for some years.

I need help to explain the learning a foreign language in America and describe the continuation to the supplied statement about learning a second language in America.