Does she not think I know how to deal with a baby?

I'm 51, soon to be 52 in a few days and my wife is 50. I got full custody of my daughter when she was about 2 years old. I've raised her all by myself with the help of my family. I've helped an ex-girlfriend of mine raise her daughter when her own father was killed a few years after she was born. She now has 3 kids of her own and they all call me granddaddy and yes, I have a hand in raising them as well. My own daughter had my first bio grandchild earlier this year and we share in the duties of watching her during the day so my daughter can work. Both my wife and I work from home. If she's not here with us then she is with her great-grandma (my mom) or with her great-aunt (my sister). My wife has this idea that men just don't know how to take care of babies. If I didn't know how to take care of a baby then why did the judge grant me full custody instead of joint custody? To me, her idea is a sexist one for women to think that they are the only ones who are capable of raising a child. This morning my daughter brings in the baby and we put her in the nursery on the bed and turned on Nick Jr on the TV. I get a text from my wife a few minutes later to say. "I planned to go somewhere after I got off today but I see that I can't now." My response to her was, "why can't you?" She then tells me that with the baby here she can't just leave. I told her that I really hated the notion that I couldn't work and tend to a baby at the same time. I guess she feels that since I can't actually birth a baby I am going to be totally lost when/if she leaves the house to run an errand. Do most women think that only they can take care of a baby? I'm not so tied to my desk to where I can't go put a bottle in her mouth, change a diaper, or play with her for a few minutes. We share the duties while she's here but I guess if my wife leaves then I'm going to put her socks on her hands and put the diaper on her head. (Sarcasm) Why does she think I do not know how to take care of a baby? I've even told her to stop doing me like that and that seems to piss her off because I'm (a man) telling her to stop doing something that bothers me.