The mothers should attempt discretion, and the potentially offended (especially) should avert their eyes.
Then everyone goes about their day quite nicely, and the world continues in the grace of G-d.
No way I’m averting my eyes.
If a female (and I’m going to use medical terminology here, so bear with me) wants to bare her booby in public, then I am going to look.
Why? Because I am a guy. To see a booby would be the high point of my day, and if the chick is so insensitive to that, then it is her burden to bear.
A chick who bares her booby in public has broken the social contract the holds together our civilized, Western culture. That is, both parties have responsibilities to uphold for the contract to be valid, and if one party fails then the contract is no longer valid.
Her responsibility is modesty. My responsibility is to not overtly look down her blouse when she bends over to pick out Chobani yogurt from the refrigerated case.
Thus if she eschews modesty, as our culture defines it, all bets are off. I’m agonna look.