I didn't do an archaeological study, or conduct a survey, but I have seen it done several times in my life, the first time in the incident I mentioned. I got the impression, both from my mother's explanation, and my own observation of the reaction of strangers, that it was neither offensive nor particularly noteworthy. I did get the impression, from every time I have subsequently witnessed the operation, that it was not polite to stare, but perfectly all right to continue with whatever you were doing.

I understand that this may not be the same in other cultures, or that perhaps even mores change over time in any one culture. But I was still surprised by the report. It just seems like lately, it has become an issue of public controversy, with factions lining up on opposite sides in some kind of public debate, as if it really mattered.

I would imagine that in a public place, natural modesty and consideration of others would demand some token effort at covering the breast would be expected, but that it might be impractical depending on circumstances, what one was wearing, whether you were seated or not, hand a hand free, and whether
or not there was a place to retire to. I've seen breast feeding on a public vehicle, at a friend's dinner party, on a park bench, and several other times where I can't remember the details. I just didn't feel, after my initial encounter as a child, that it was all that important. I felt it was good manners not to stare, and avoided doing so.