When I was in high school some girls chose to not wear bras. It was no big deal, those with manners simply didn't notice what might have been visible in some circumstances if you stared at the girls. And if they did notice, they kept it to themselves.
What happened to manners and common sense?
Qualities like manners, common sense and honor disappeared from society at some point during the downward slide we’ve been on since about the “beat generation” became a thing in the 1950’s. Started out slowly, but accelerated around the late 1960’s.
They were thrown out with the bras.