I'm Vietnamese.

The Vietnamese people you mentioned who escaped to the US decades ago were refugees. They were escaping a country where bombs were being dropped daily, famines were normal, and literally millions had died due to lack of food.

The literacy rate was 3%. In other words, the majority of those poor folks are not even fluent in writing their main language. Many of them, including my relatives, expressed the wish to learn English, but as you can imagine, it's pretty challenging. Some picked up enough to communicate, some gave up and depended on their children/grandchildren for translation. They had seen war and hell; being alive is a blessing.