How are those less clear discriminators?

I am sure I could find a study showing that attractive people have a better shot at getting the job. Height is attractive.

When I said clear discriminator I mean they are binary: either make or female, either black or white. Height or attractiveness are more diffuse for some people you can be tall/attractive but not for others. Gender and race are clear.

In my opinion height or attractiveness play a role in the society (a big role), but it is easier to talk about gender or race because the clear distinction, bigger represented groups and historical reasons.

>but it is easier to talk about gender or race

It's intellectual laziness.