[UncleMeat]

Wealth, education, and any number of other categories also matter a ton. We exclusively use gender and perhaps age to label people. Why?

[MaxBarraclough]

We don't. We use titles like 'Professor', 'Captain', 'Pastor', 'Doctor', and 'Congressman'.

[iguy]

Because education didn't exist for most of the last few thousand years. Wealth did, but I guess it wasn't worth modifying your speech of every day to encode that today isn't the one day a year you happen to encountered a nobleman.