At my school, (I'm admin, not on reception), there are usually at least 5 packed lunches on the counter at lunchtime which have been dropped off by various parents during the morning, (along with 10 PE kits, 3 lots of cooking ingredients, 2 library books, a pair of glasses, some trainers and several door-keys
).
If a child realises they haven't got their lunch, they come to the receptionist to see if it is there, or, if not, borrow lunch money to be paid pack the next day. Our receptionist isn't allowed to leave reception unattended, and there aren't any "spare" staff to run around dropping off lunches and PE kit to all and sundry, but she does tell parents she will "do her best". More urgent items like the door-keys will usually be sent with the teacher, but aren't passed on until the teacher is in the staff room at lunch.
The only job that is ever refused, (politely, I might add), is "Johnny forgot his homework and Miss Smith says he'll have detention if he forgets to hand it in again, can you deliver it to him so he doesn't get into trouble?"
We always say no to that one, and explain why. I would imagine those Mums post on here calling us rude and think about complaining to the Dep Head! 