Japanese people's response to "How are you?" (日本人の "How are you?" への返事)

In Japanese junior high school, Japanese people learn to reply with “Fine, thank you. And you?” for “How are you?”. Besides, we learn as though this is the only correct reply. If you are asked to fill out a blank of conversation example like below on an exam,
日本の中学校では、日本人は "How are you?" への返事を "Fine, thank you. And you?" だと教わります。その上、それが唯一の正解であるかのように習います。もし試験で以下のような会話の例の空欄を埋めなさいと言われて、

Ken: Hi, how are you?
You: _________________

and you write “I’m good!” or something, your teacher might regard it as a wrong answer.𿘨
"I'm good! などの答えを書いたら、先生は不正解とみなすかもしれません。𿘨

I believe this is one of the reasons for that a lot of Japanese people are not good at speaking English. English lessons in Japan are just like English quizzes rather than learning language.