Tush, that's discrimination at an institutional/business level and not by a personal entity/aka body). For the most part, I think that era of institutional discrimination has diminished to a greater degree.
While being a provider could be considered a private "business" enterprise, none of those other jobs/institutions result in a delivered service that includes direct personal relations (ala intercourse or other) with the patron.
Therefore, the freedom of personal choice/preference by the provider applies. A woman's body is her own personal domain and there is nor should ever be any requirement for her to provide equal access to anyone regardless of her personal choice. If a provider wants to see everyone, that's fine as it's her own freedom of choice.
What I do have a problem with is the potential to label or harass a provider for her choice to be open and see anyone or be selective about the clientele she accepts. It's her body, it's her life, it's her choice to be open/selective/or closed.
If people want a list, please make it all inclusive to cover all flavors of the rainbow you agree to meet. Little clever color coded icons will be just peachy!
To be honest, this is all becoming pretty silly. Just ask the provider.