It is all political issue, the school have the funding for it, if you have an asian look, the school will place you in the ESL class.
The fact: A vietnamese woman married to a white American, their children have asian look. The mother took her daughter to school for registration, her daughter was placed in a ESL class. The next day, the father took her to school and ask the school why she have to be in the ESL class, the school claimed it was a mistake.
Additon: My daughter was told that she was not good at English, so she challenged the English credits by exam at UCLA and passed, this means that her English level was more advance, she didn't need to take the English class.
In response to the question. In US, the native born americans may need to attend the ESL class if the schools are funded.