I've seen a National Geographic documentary on breast ironing a while ago, the documentary is actually about taboo practices worldwide. It's simply barbaric. You talked about breast disfigurement as a result of this barbaric practice. Yes, it is obviously seen and the thing is , it's not only physical disfigurement that the female child suffers, I can only imagine what kind of emotional trauma the child will get from it.
What's worse is that the female child's own mother does it! Just as the mother's mother before her has done. You see, this horrid practice, as is with female genital mutilation isn't just because of poor sex education, although it's a huge part of it. It's a whole lot about culture. I mean, this is their way of preserving their female children's chastity. The breasts are ironed to prevent it from developing, thus keeping men away.
As with female genital mutilation, which has different methods by the way. There's clitorectomy, removing the clitoris and the most severe form which is infibulation, which is removing everything, clit, labia minora and majora, and just suturing what's left to leave a tiny hole for urine and menstrual blood to come out. And basically, this is done in certain african and middle eastern countries because their women are taught that what's between a woman's legs is bad. And that the clitoris, the center of pleasure is evil, which will lure them to have premarital sex and what not.
So yeah, it's both a lack of or extremist understanding of sex and cultural influence. And yes, all cultures have their own women and men's right of passage. But at some point the line should be drawn, especially when it is mutilation and abuse.
A lot of people don't know about this, and I commend you for bringing it to light. I always believe that raising awareness is a huge step in helping stop abuse.