You pack and give food to the 5-10 year old. They feed themselves.
You supervise the 10-teenageish to gather/pack their own food.
After "teenageish" you do in fact leave them out on the hills to fend for themselves...
... and part of fending for yourself, is to know when to ask for help. But the terms of help is hopefully between two capable humans at that point.
In the school system, I would expect that teachers are not asking 5-10 year olds to do complicated tasks. But to do simple tasks outside of school hours (homework) and know how to dress on any given day is totally appropriate. Parents can assist their kid to be so organised as and how they can. But the kid themselves are responsible to the school if they aren't.
> know how to dress on any given day is totally appropriate
No, 5year-olds can't [all] track the three different "special" outfit days in a week and know whether to take in the clothes or dress in them in the morning. Many five-year-olds don't know which day comes after which, and most don't have literary skills to write themselves a reminder or to log on to a computer calendar and check. They need parental help. I can tell you that some of us parents find it difficult to track these things and keep everything straight, too.
Teachers absolutely do ask children to do tasks they can't achieve on their own (eg. I guess maybe rich families might have all the stuff to do an impromptu craft project but if you need pipe-cleaners and black card to make a spider for Hallowe'en then you need an adult to shop for/with you). But parent-child cooperative projects lead to better outcomes and children feel more engaged when their parents take part with them.
In our house there's no space in our kitchen for each person to make their own sandwiches, and that would be super inefficient. But yes, teenagers could take turns making for everyone; that's not good for our family though.
