I've had this problem for years, I hoped the new family friendly style features would improve some of it. I have problems with nannies and butlers so I stopped using them. I was sent Elders most of the time who did very little work or none at all and I don't like to judge on appearances but they looked, well creepy! I'm on Console so no mods and we are penalised for using cheats (honestly, have they played the Sims? Obviously not).
The hired staff just stood there or kind of shuffled around, they did nothing for the children. My Sims would return from work and had to start cleaning up the house and the kids needs were so low that they needed urgent attention or they'd be taken away. It was so frustrating to watch if the Sim was at a regular career job, I would just be watching the staff do nothing and depending on the age of the child, not be able to control any of it. At least with child age Sims you can still control them, so I could get them to get their own food and pick up around the house. It looked so neglectful that it made for uncomfortable viewing, seeing a distressed little Simlet being ignored.
So my workaround was for a parent to be self employed. I use Register with Ministry of Labour a lot. The Sim with the worst nanny was an artist. So she quit her job, painted at home and opened a retail lot. I added a family flat there too so she could work there and have her son on site with her and still have home comforts around him.
With child age Sims although they can be left at home, I'm not keen on that so they join after school clubs if their parents are both at work. IRL the kids in my circle don't get left alone until about age 14. There's a few times I've met the school bus on the doorstep for my friends tween kids lol...and for some reason it's always a day they get off the bus in tears for something so I always carry chocolate! But with the Sims I recommend not saving the game while an infant is being minded, so that if they are taken away you can cancel the day by exiting without saving...and then fire the nanny!