She's presumably paying the nanny some kind of market rate. If instead she were to bump the pay up well above market rate, she would either attract significant competition over that particular nanny job (presumably not the goal), or be effectively giving a large cash handout to someone basically on the basis of happening to be around at the time. It doesn't seem obvious that this is a useful or desirable course of action, either on the basis of addressing inequality in the economic system or optimizing your interpersonal relationships.

(Also, I feel like I may have some kind of disconnect here, because I'm not anywhere near those income levels, but $6 bread doesn't scan as horribly unreasonable to me.)