For a while now I've curated a subreddit on Reddit. It's an alt universe where women's fashion exposes the boobs and that's accepted and everyone is ok with it.
After some clumsy adjustments to my C204 Time Displacement Unit, I find myself stuck in a parallel universe that's almost the same as yours.
Except here, women's fashion embraces the exposed breast.
Women say "I'll wear the oneboob dress today" (a style that covers one breast but exposes the other), all clothing stores stock a range of "open" dresses and tops that show both breasts in a wide variety of styles, and even the unadventurous can wear "invisible" tops that "cover all, show all"
It's from this alternate universe (which I call "AltBoobWorld" because I know no better) that I'm reporting, with photographs and descriptions of the fashions here.
I'm not the only time / dimension traveller here - their surprised looks at seeing women casually walking around with their boobs out gives them away. It takes a little while to get used to things here.
Fellow time travellers are therefore welcome to submit their own photos and descriptions.
The fashion must reflect our alt reality: boobs are on display but not being flashed, clothing is not simply being lifted or pulled away. The fashion of exposing one or both boobs is normal in our world and the wearer will appear comfortable and nonchalant. It's more about clothing than simply being topless.