I think along with alot of people it comes from the older generation and what there experiences were and we now live in a much more accepting society to them i believe. I mean if you speak to the older generation and so forth they will tell you they all covered up or would wait to feed there baby until they could be alone or in another room because it just wasn't acceptable practice in front of others and i even found i would get looks from that age group but i didn't care as my baby needed feeding. It is like the whole society has to be retrained in what to do with breastfeeding when it is something that should come so natural.
I have found the opposite generally. I was feeding my son on a crowded bus once and his legs were kicking the old man next to me who didn't mind at all. And two older ladies saw me and my H said they were quietly talking to themselves about how lovely it was to see someone freely BFing their baby.