Why, according to the flower girl, should the note taker be ashamed of himself?

Higgins's ability to pinpoint the location of origin of members of the crowd means not only that he can tell what part of England, or even what neighborhood of London, they are from, but also that he can probably guess fairly easily their socioeconomic status. In the early twentieth century, social mobility in Britain was slim to none. His assertion that he can turn a flower girl into a duchess is rather offensive to the flower girl.