Years ago there were not many good channels for learning English, only a handful worth watching. I used to watch one whose host joked about what makes English "proper", his punchline being that it is proper because the country is rich.
What I have noticed since
After years of studying, teaching and talking to people, what I see is that Vietnamese learners are embarrassed to speak English because they are afraid of sounding wrong. It is a damaging belief and a badly mistaken one.
The word "the"
In my classes it is rare for me to single out a word someone is not yet saying well. But take the. Southerners seem to find it easier than northerners, because the sound does not exist in our own language and the mouth simply has not done it before. It needs practice, nothing more.
In a lesson yesterday, after roughly two months of study, one student got it, and was delighted with himself. He will now find similar sounds far easier.
Had I told him on the first day that his the sounded odd and was wrong, there would have been no day sixty for either of us.
What people actually need
What lets a learner train their mouth, study on their own and enjoy English is feeling safe enough to try. Not the fear of sounding wrong and being laughed at.