Not old enough

I believe in gradually giving my kids more and more independence as they demonstrate ability and responsibility. Why do for them what they can and want do for themselves? Apparently other people think my kids aren't old enough to do some of the things they do.

Incident 1)
A neighbor asked to borrow something, and said he would return it in a few minutes. The kids crowded around because they are always curious. A few minutes later the doorbell rang. Wander and I were upstairs, so Sparkle looked through the window, saw that it was the neighbor, and hollered to us who it was. She then proceeded to unlock the door. Only, that made the neighbor uncomfortable. He asked if she knew who he was. He asked if it was okay for her to open the door. He checked to make sure that she wouldn't open the door to a stranger. Only then did he let her continue opening the door.

How old do you have to be to open your own front door to let in a neighbor whom the whole household knows and expects?

Incident 2)
The girls and I were at the library for our weekly library trip. I was checking out books at one self-serve station, while Glitter checked out her books on the station next to me. Suddenly a lady starts grilling Glitter about why she's there "by herself" and telling her that she's too young to be there. At first I assumed that the lady was just grumpy because Glitter was taking so long. So, I politely informed the lady that (1) there was a third empty check-out station, (2) Glitter was with me, and (3) Glitter is used to checking out her own books. The lady lumbered to the empty check-out station, muttering that little kids "shouldn't be allowed." When I asked how old would be old enough, she answered "At least 18."

Huh? Eighteen to do what? Go to the library? Check out their own books? I don't get it.