What are wives hoping to accomplish when they undermine their husband's authority in front of the children?

Your wife has bad parenting skills. Plenty of men are the same way, so don't further complicate the issue by turning it into a ist issue. If you couch it in those terms, you're going to make it worse. Parents should discuss their difference of opinion in private and then show a united front to the children. Explain this to your wife and don't insult her while doing it and you might get somewhere. Otherwise, I think she might be doing it out of rebellion because of your ist tone. So help yourself out by dropping that attitude.