Hong Kong education, a reason I come US...

In Hong Kong, at the government level, although Chinese is one of the two official languages, all government documents are drafted in English in the first instance and then translated into Chinese. Moreover, one of the most important criteria for civil service recruitment, particularly at the administrative officer level, is English proficiency, both spoken and written.
At the business level, all jobs ranging from clerical staff to top-level management require English and for senior positions, a good command of English is essential. A good command of Chinese is but merely icing on the cake. In short, a monolingual English speaker can operate fully at all levels but not a monolingual Chinese speaker.
Given the situation, it is not surprising that Chinese-medium education is simply not a viable alternative for parents and students. And the use of English as the medium of instruction can best equip the student for our future jobs.