This is no help with your specific question, but I too have noticed a different mindset on money matters and would appreciate a pointer to good information on the topic if anyone can give one. As you noted, people do seem open about what someone's annual income is -- as if having such-and-such a year is an inseparable personal characteristic, like having red hair. Also, there seems to me to be greater attention to personal accounting between close relations, and less of a tendency to share or help out than we might feel proper in our time.

Examples: Fanny and John Dashwood in S&S as the obvious extreme example; the none-too-generous financial support of the Austen women by their brothers; the recording in JA's letters of petty debts between Jane and Cassandra. Also, in Parson Woodforde's diary, when the Woodforde siblings' father dies, Parson W inherits the family home, his sister continues to live there -- and is charged an annual sum for bed and board. Altogether indicative (to me) of a different attitude toward money.