Why does the note taker believe that the flower girls dialect hinders her ability to transform her station in life

The note taker believes that the flower girl's dialect hinders her ability to transform her station in life because

for her to move into the middle-class that she ardently desires, she must learn to speak like a member of the middle-class.

Explanation:

But her dialect betrays her.  Therefore, she must learn proper English phonetics.  The flower girl attentively learned from Professor Henry Higgins, who transformed her Cockney dialect by teaching her the correct English phonetics.  In this George Bernard Shaw’s “Pygmalion” (1914), a comedy about the importance of the English phonetics for transformation and climbing the social ladder, one learns the importance of determination.  Determination enabled Eliza Doolittle, the flower girl, to change her station in life.