If the mom is at home then she isn't showing her kid(s) that they can go out in the world and make a differece and make there life better, when the mom is out working she may not spend more time with her children because she teaches them that if they put there mind to it they can do anything and that is what childern want in there mom they want to be able to look up to there mom and say my mom is a hard working mom and she can do what ever she wants.
Working moms know more about the outside world than housewives do. Working moms deal better with money and they are just smarter, maybe not ALL the time but housewives are cooped up in the house with kids all day while the mother works, deals with adults, money, and other things that make her wise and more helpful to her kids
Working moms can advise their children just as well as stay at home mothers can, and they can help when the kids want to get their first job too. Really the only argument that can be made about working moms not educating their children is one that ends at saying women shouldn't be in the workforce, and I'd like to think we've gotten past that.
Many working moms give their children a good role model and they also spend a lot of time educating them in various aspects of life. But lots of stay at home moms do exactly the same thing. What matters is the quality of parenting and the dedication to the child's well being.