It is sad that children don't know that the primary function of breasts is feeding babies. I am not disputing that there are many who don't. In practise, however, never, in the 3 years+ I spent feeding my children, has a child or teenager had a reaction that made me uncomfortable. Mostly. people don't pay any attention at all (which is great, I actually don't want people drawing attention to the fact that. however discreetly, I have my boob out in public - I would feel horrible if I thought that people were discussing me on line afterwards) One middle aged gentleman was lovely when I was feeding my youngest at an airport. He was sending his teenagers to buy drinks. I was sending my 7 year old to buy a drink for himself, and trying to keep him in my eyeline (I was right outside the shop) and, he simply checked whether he could get me anything, since I couldn't do that, and a 7 yr old is barely reliable enough to get themselves something.
I mean, I know people DO have much more negative experiences than I did, which can be really damaging for the individual and the breastfeeding rates generally, as people do get very anxious about feeding in public - I know I did. But really, it is unremarkable, so, mostly, people are not bothered.