I agree on the points on BFing from commentators, but I think the main point of the article was addressing a slightly different, albeit, related issue - the working mom vs. the stay-at-home mom.
My view of HK vs. North America is that in HK there seem to be a lot more stay-at-home moms in the expat community. I think this is probably because these women are trailing spouses? I do see competition and badmouthing across both groups, but it seems to be stemming from someplace different, which is that working is less about financial need and more about choice. I think in North America and maybe among locals in HK, moms might choose to work, but many times they need the dual income, so there is no 'choice' to debate. I wonder too if some of the negativity is because people who are trailing spouses sometimes gave up professional careers and their sacrifice is not appreciated. I have heard criticisms about moms trying to keep busy by starting businesses that are potentially not profitable (photography, cake baking, party planning) from other working moms, saying those aren't 'real' careers. I've also heard criticisms of stay at home moms who are perceived as spoiled because they can afford to shop as a hobby and vacation in private villas in Europe and Southeast Asia, have drivers, etc.
When I was in North America I think there was a lot less competition. As diverse as HK is, the expat community seems fairly uniform, because most people work in some sort of finance or finance-related job. Therefore how much you make, how much you spend, what your work title is, where you vacation, etc, becomes a big focus. It's unfortunate, but that's my observation.