Why isn’t my uncle fluent in English, despite spending most of his life in the US?

He came to the US from Vietnam when he was 14 and went to high school. He’s 34 now.

He still makes plenty of grammar mistakes, and his English is understandable yet still unpolished.

He owns a nail salon in a city with a very small Vietnamese population (like less than 60), and of course he has to speak English to communicate with his customers.

“Is anyone knows where can I buy a lots of new stuffs for my kids? They are decided to playing new toys. I love watching them just lets enjoying their childhood in present. Love is not for the one whom is not appreciated the present!”