I think having sex with someone is a lot more personal than selling them a newspaper so that's a ridiculous comparison. Say for the sake of argument a girl does have a bad experience with a black/asian (or white) guy then she might feel intimidated by a punter of that ethnicity and that's not going to be good for anyone.
I'd say if a girl has a right to video every punter as he enters her flat, or have a chaperone in the room, then sure take everyone. Til then you have to give them a choice.
Nobody gets this upset when girls exercise their right to refuse older/younger guys.