One of the absolute biggest challenges is women's support networks. In cultures where bf is the norm, it is understood that it is very hard and demanding, mothers are given support to do it and helped by the older women around them, who often have a nursing baby/child of their own. In our society, the nuclear family, frequent lack/distance of extended family, and the fact that today's mums are the children of a generation that largely formula fed does not allow for this - and in a lot of cases, as women leave childbearing later, even if your mum or whoever did bf, oftentimes it was so long ago she doesn't really remember enough to be helpful (not to mention the cultural expectation that women "get back to normal" as soon as possible after childbirth).
Most women want to bf; most women don't. Very few women who did wish they hadn't. There is a gap between these facts that needs to be filled with information, support and the normalisation of breastfeeding along with an understanding of what it requires.