Why are there many English movies without subtitles?

In Taiwan, it is common to see a Chinese movie with Chinese and English subtitles at the same time. Why Chinese subtitle? It seems not make much sense. If everyone speak Chinese and then, the audience can listen well.

Tracing back to the history, not many people are familiar with Mandarin, which has been then set up as the only official language by Nationalist government since the 1950's (by speculation). At that time, many people in Taiwan only spoke Japanese and Taiwanese. Mainlanders following from the Nationalist government were also from different provinces with diverse dialectics. They were not relatively good in Mandarin. Fortunately, for the Chinese, they speak different dialectic but can recognize the same Chinese characters. Therefore, that a movie has subtitles with Chinese characters quite make sense. Why English title? Prepare to foreign audience, I guess.

This is a historical explanation. Another linguistic explanation, I guess. Chinese is not a language by pronunciation. English is a language by pronunciation, although it is not so matching as Spanish or French. When you heard the sound, you can spell it almost. In other words, to learn English should try to listen more sounds and memory the sound than the vocabulary. When you can say it, you can use the word and almost spell it in a rough right spelling.

In brief, to learn English in a easier way  is to listen and speak rather than memory the vocabulary. Because if you can know how to speak, which means you have know the word more than half.

I might need advanced arguments to support this point.