Especially if it's the type of business that only caters to a certain demographic, like a hair salon that only caters to women, or a kids' group that only caters to minors. I once worked in a gym in a neighborhood that had a large Hasidic population, and the women could not work out with men. The gym set up classes three mornings a week with a female instructor, and men were not allowed to take (or teach) that class.