In the novel Pygmalion, what is Eliza's reason for wanting to speak properly?

From the text:

THE FLOWER GIRL. I want to be a lady in a flower shop stead of selling at the corner of Tottenham Court Road. But they won't take me unless I can talk more genteel. He said he could teach me. Well, here I am ready to pay him--not asking any favor--and he treats me as if I was dirt.