> these subjective judgements often reflect an unconscious bias

Are you sure it's unconscious?

Say it's conscious (eg "I like my hires to be scrupulously polite and deferential") and that overlaps with a cultural norm - is that problematic?

How about "I like my employees to be extremely punctual". Or "I like my employees to be dressed smartly". Is correlation with any subset of people sufficient to be illegal? Should it be?

Liking your employees to be extremely punctual is pretty objective, but the other two are potentially problematic if you do them wrong.

One example where this comes up a lot is hair. People from backgrounds where straight hair is the norm envision "well-dressed" to include neat and orderly hair, often more neat and more orderly than people with type 3 or 4 hair can actually achieve. So many areas where both straight and curly hair are common have found it necessary to stipulate in law that any grooming expectation you impose has to accommodate the full range of natural hair textures.

You’re not wrong, but that bias is not stemming out of Racism imo. Also I’m not saying that the bias is acceptable, but it shows a different kind of social problem that often transcends classes and gender.