Having the best of both worlds, that's what I'd call it.
This is incredibly naive of what single parents have to go through. And yes, they are single parents.
I have a friend who unfortunately split from her husband a couple of years back. The 'best of both worlds' that she puts up with is awful. She has sole responsibility for getting her child up and fed and to school on time, making sure all homework is done, making sure all her daughter's social stuff is organised and so forth. She has to make sure she can get the child to all afterschool and weekend activities. If she happened to have two children, she'd also have two needs to sort out by herself. She can only work between school hours because her ex was already working full days and refuses to change.
She can't go out at the drop of a hat without arranging paid-for childcare (obviously I help out when I can). She has to argue for every bloody issue for her child. Every spend on the child has to be justified to him. She didn't get the car, so every party has to be managed by bus (again, I try to help out where possible).
She sees her dad. The live less than a mile apart, but the difference is that he sits in his house all day while she's raising a child, and the daughter just goes to him for sleep and fun (and he often foists her onto me on the days he can't be bothered.)
I, in contrast, still have a husband within the home.
I can leave for work at 7, knowing that the children will get to school. I can have a headache and retreat to my room for a couple of hours knowing that someone else will occupy my children. I can go for meetings at the school or elsewhere knowing that DH will be around. If there's a day I don't fancy cooking, the children won't starve if I don't rouse myself to do it. If something happens at the kid's school, we can talk it through together without fearing that someone will say we dealt with it in the wrong way. We both have each other to juggle all the complex needs that children tend to have.
Having an extra adult who has parental responsibility within the house is massively different to having one who will be prepared to take on his or her children only at times when the children will be easy.