Whys said what I was going to say about the lunches. Thanks Whys!
As for the milk, do the kids ever fetch things for you? When my older kids were growing up, if one of us wanted something from the kitchen we'd ask if anyone else wanted anything. That went for kids as well as adults. We didn't ask someone else to wait on us. When I was a kid, it was the same way.
No, my kids didn't expect me to jump up from our meal to get them more milk when they were old enough to get it for themselves. And, I didn't expect my Mother to do it, either.
Do you ever ask the kids to get you anything? I think doing each other "favors" is fine...as long as you aren't expected to be their servant. They need to learn that helping each other works BOTH ways.
When they get out on their own, that's how it will be, and now is the time to teach them, for their own good! It's not doing our children any favors to let them grow up thinking they can expect other people to wait on them.
Nature abhors a vacuum. And so do I. ~Anne Gibbons