DD is 13. She's always had packed lunches for school, and since she was 5 I've made them up in the morning while she's getting ready for school. It takes 2 mins and I do it while the kettle is boiling for my second cuppa of the day.
My friend is totally shocked that I don't make DD do it.
TBH it's never even crossed my mind. It's a two minute job and I don't mind. It's not like I'm cleaning up a huge mess that she's made, or putting her clothes away for her, I'm just making her lunch in the same way that I make her dinner - out of habit because it's my job as a mum!