In the Barba Azul Cabaret in Mexico City, the women dance and drink with the men who can afford it. In the little restroom upstairs, Mami looks after them at the start and end of their shifts. As long as Mami gets her tip, she looks after the bags, makes sure there’s enough toilet paper, and is always ready for a comforting or supportive heart-to-heart. She’s quick to deliver o…