I think there is a similar trend of ageism. It is common for girls to seek/only see "mature/older" gentlemen. As a younger guy (well, 35 is younger in this biz as far as I can tell), I've never been asked my age before or during, except casually when it wouldn't matter. I don't know if the racists check either. Not that it matters.
I had an encounter with a black provider a few months ago. It was late, the experience wasn't anything special, but I was dismayed when during the after-chat she went off about the biz. Here is what I remember her complaining about:
Young black men, because she said they are "pushers" and are always trying to get more from her.
White girl providers because they are freaky and do "dirty" things, and ruin it for everyone else.
Asian providers because they are the "dirtiest". and ruin it for everyone else.
All providers who charge less than her, thus dictating what her rates have to be and ruining it for her. "We should all just set the rates, and nobody can go lower". Fascist. Hag.
Everyone in Ohio, because they were all jerks.
Then she said she was gonna get high.
I still laugh at it all, although I think it is sad.
What else can you do? You cannot force reason upon them in their hearts. We live in a country where homosexuals can't get married. Where women are still paid less than men for the same work. I am a hetero white male, and although I've experienced racist/sexism/ageism and other prejudices in life, it has never really affected my sense of self. I know a lesbian who has described horrible treatment at such random places as hardware stores and jewelry shops. I don't get it. I have hope for humanity, but at the same time, feel disconnected from it.
So yeah, I agree with you.