The conflict in Pygmalion demonstrates that class differences are not as rigidly defined as people might believe. Furthermore, qualities associated with particular social classes are often a reflection of learned behaviors, which are malleable.
In the early twentieth century, the wealthiest social classes in England, who had always enjoyed a...
stable sense of social importance, found themselves being squeezed out by a growing middle class. It thus became even more important for them to cling to the rigid social hierarchy they had always known. This is demonstrated when Higgins tells Eliza that she can't "throw away" her new social standing on someone like Freddy; instead, he insists that she marry someone who can further her status, like an ambassador or a lord.
People of a higher social position look down on people like Eliza particularly because of the language and mannerisms associated with the lower classes; therefore, language and manners come to define one's social rank—and even their worth. Yet Eliza proves that people can learn to master the nuances of mannerisms and language associated with the upper classes. Therefore, these qualities aren't innate traits belonging exclusively to the wealthy. When Pickering complains about how much manners have changed since he's been away in India, Clara points out that "it's all a matter of habit" and that "there's no right or wrong in it."
Eliza points out to Pickering that "the difference between a lady and a flower girl is not how she behaves, but how she's treated." Class differences, therefore, generate conflict among social groups because people feel entitled to treat the poor with less respect than the wealthy.