I supose it depends on how you define 'advanced country', HH. Even the women working in the fields in India 'hide' their breasts away. Their midriffs are open for all to see, as is their cleavage, but the actual breasts are tightly controlled in their sari blouses or other top-half attire.
I was just thinking of the way popular culture in the west portrays breasts. I suppose (not being a woman) I am not able to fully appreciate the problems associated with carrying a couple of lumps of semi-mobile fat around all the time, the need to keep them under control and the need to ensure that they don't get in the way when I am doing something. Hence the enclosure.
What appears to be the important constraint in the west is that the nipple and areola cannot be seen. This secrecy - to me - seems close to fetishism. Yet these also are parts of the breast of most interest to babies. Perhaps it from this paradox that people' unease about seeing breastfeeding arises.
Does any else recall an incident a few years ago, where a guard threw a woman off a Virgin train for breatfeeding? I recall that Richard Branson made a full apology. And (though I may have got this wrong) the guard suggested she feed the baby in the toilet. I wonder if he eats his food in the lavatory?