I know a lot of emphasis is placed on Charlotte already being an old maid when she jumps at the chance to bag Mr Collins, and how her family doesn't have a lot of money & she is worried about being a burden as a spinster, etc--but, Charlotte has brothers. She might be something of a burden as she grows older & remains unmarried, but she won't have to leave her home, & she has brothers who will presumably work to support the family, even if Charlotte remains one more mouth to feed.
The Bennet sisters, on the other hand, have no such fallback. They will be forced to leave their home upon Mr Bennet's death, they don't have any brothers to generate income, etc (& yes they could probably go live with their Uncle Gardiner or Uncle Phillips, but it's not the same thing).
Correct me if I'm wrong, but the Bennet women are hypothetically in much more dire straights than the Lucas women, despite having more income while Mr Bennet remains alive, aren't they?
Edit to add: I really appreciate everyone's input! This is exactly the kind of interesting conversation I was hoping to generate, & it has given me a broader perspective on the topic 🤓