Many quotes show Pride and Prejudice to be an analysis and criticism of traditional class distinctions. Two follow, and I strongly suggest looking at well as Elizabeth's impassioned response to Lady Catherine de Bourgh when that grand dame comes to tell Elizabeth that she is not good enough for Darcy.
In the first quote, Austen is being ironic: she does not, in fact, think of the Bingley sisters as "very fine ladies." She is using a superficial, outward, and searing description of what a "fine lady" is to outline that the sisters are in fact spiteful, shallow, conceited people who put on airs because they have money:
They were in fact very fine ladies; not deficient in good humour when they were pleased, nor in the power of making themselves agreeable when they chose it, but proud and conceited. They were rather handsome, had been educated in one of the first private seminaries in town, had a fortune of twenty thousand pounds, were in the habit of spending more than they ought, and of associating with people of rank, and were therefore in every respect entitled to think well of themselves, and meanly of others.
In the second quote, Elizabeth shows that she is mortified by her friend Charlotte making what, in the eyes of conventional society, is a very fine match to a gentleman who has a good living as a clergyman and will inherit an estate that will add to his fortune:
but she could not have supposed it possible that, when called into action, she would have sacrificed every better feeling to worldly advantage. Charlotte, the wife of Mr. Collins, was a most humiliating picture! And to the pang of a friend disgracing herself, and sunk in her esteem, was added the distressing conviction that it was impossible for that friend to be tolerably happy in the lot she had chosen.
Elizabeth's strong feeling that Charlotte's sensible, worldly, status-enhancing match is a disgrace because Mr. Collins is a jerk points to the alternative mode Austen envisions for organizing society. In Austen's moral universe, a just and healthy society would be organized to reward and celebrate the inner worth of human beings, not what they wear or how much money or how many titles they have. Instead, kindness, compassion, intelligence, good sense, and wit would matter most in ranking them.