How can you talk about dear dear Elinor like that? I contradict everything you say! ;-) *cough* OK, seriously though, here come some details by way of proper discussion.

Elinor is self-reliant and calculating, perhaps because nobody else in her family is reliable or inclined to face hard truths. She's not above lying. (Ch21: ...and upon Elinor, therefore, the whole task of telling lies when politeness required it, always fell.)

Lucy is self-reliant and calculating, perhaps because nobody else in her family is reliable or inclined to face hard truths. She's not above lying. (Ch24: "... I can safely say that he has never gave me one moment's alarm on that account from the first.")

So far they are equal. But how do they apply their methods? Elinor mainly looks after others, and Lucy mainly looks after her own interest. IMO this difference is only justified to a small degree by wealth, and the rest comes down to character.

Is Elinor too quick to judge Lucy as illiterate? She made quite a point of reserving her judgment of Mr Willoughby and waiting for evidence. I think it's more likely that JA meant there to be plenty of early evidence, but spared us the details and kept the story flowing.

Is Elinor conceited, and does she attach too much importance to Lucy's illiteracy? I don't have any evidence to hand, so will call that one a matter of opinion. Either way, she doesn't let any conceit show in her behaviour, and certainly doesn't brag or flatter like Lucy.

Is Lucy's illiteracy a circumstance outside her own control? Surely she could have picked up some education at Longstaple, at no expense, from her benefactor uncle?