why does this bother me?

For starters I work 40 hrs a week, I pick up my two kids from school, go home, make dinner, do dishes, clean the house, take care of the animals. I do a lot but before today I assumed that's just what motherhood is. Then at a family gathering today everyone is sympathizing over a family member complaining that she's too exhausted from watching the kids to cook or do housework. She is a sahm of two kids. Her husband works 48+ hrs a week, he comes home, cooks, does dishes, cleans the house, AND watches the kids while she takes a nap. She doesn't even cook for the kids while he's at work. They eat cereal and microwave dinners! Maybe I don't understand because I'm not a sahm. But I feel like if I can do all of this AND a 40hr a week job then why can't u do it with no job? I think she was just complaining to get attention and it just bothered me so much. Sorry I'm done ranting lol.
I'm married, however my husband works second shift so Monday through Friday I am pretty much a single mom. He gets our oldest daughter dressed and does her hair. He makes her breakfast and takes her to school. He does the yard work, vacuums and some laundry in the morning while entertaining our youngest before he leaves for work. If our youngest cooperates he will do some of the dishes. He cooks some Mondays so that Tuesday I can just heat up food and not rush around (ballet practice for oldest is Tuesday's). I do a lot more than him, especially since during the school year he really only has 1 kid to take care of, while I have them both when I get home. I'd prefer to do most of the cleaning cuz I don't like how he cleans. But if I have a lazy day or two he will try to pick up where I left off.