I feel like this might depend on the culture, and how late you usually eat dinner etc..

Because well, kids usually don't tend to cook for themselves so the parents end up cooking for them and eating with them.

That might be my bubble though, my friends / family have jobs that allow them to leave work around 5-ish and with school ending somewhere between 4-5, it's not that much after the kids are home. (or they pick up the kids after school).

Kids definitely can and do cook for themselves? I've also known families who would make and freeze dinners for the week so the kids just had to reheat them on weekdays. Or one parent gets home earlier and has dinner with the kids, but the other one will be later.