When working at a department store years ago I observed a woman change a diaper on the counter of the cash wrap. She was done before I could stop her and tried handing me the dirty diaper. I directed her to the rest room and proceeded to spray down the counter. I later learned that she complained about me to the general manager (with diaper in hand!) who asked her to leave the store. The store, by the way, was located in an upper-middle class community and she had just paid for a purchase with a Amex Gold Card. (This was 1986, so that was saying something).
Regarding breast feeding, I don't look. Seems rather disrespectful. Most women I've seen feeding their baby put a blanket over the baby. My guess is they want to feed their child, not put on a show.