I always think, why do all Japanese say 「髪切る」, even though many Japanese don't cut their hair themselves? (I'm a Japanese.) 「髪切ってもらう」 is almost correct Japanese, but we don't use this sentence.🤔 Similarly, we usually say 「手術する」 even though most Japanese don't perform their surgery themselves! 「手術してもらう」 is almost correct... (omitted below) I always wonder.