As long as the other person is okay with it, I don't really see the problem either.
Or an appliance that belongs to one person, but everyone uses.
Back in High School, I had a couple "friends" who acted PA when I wouldn't let them mooch off of me. It was sort of my own fault, because I got into the habit of saying yes when I was asked if they could have something, if I could pay for something, or if they could borrow something. I'll admit that it wasn't because I was particularly generous; I didn't like being bugged when I said no, nor did I like being called mean and greedy behind my back just because I didn't want to share what I had. I went without lunch a couple times when a "friend" said that she didn't have money for lunch, and I found out that she just wanted to save up the lunch money that her parents gave her so that she would have more spending money. She admitted this when I spotted her putting a dollar in the snack machine (lunch is more than a dollar, and she wanted a candy bar.
). Um, no. I need to eat too, and I'm not going without lunch just because you're saving up for a new purse.
The next time she asked me for some "spare change", I said no. She said, "Ugh, fine...I guess I'll start going without lunch myself, then." I said, "Whatever makes you happy." She went on a rant about how she "needed" the new purse, how I couldn't possibly understand because I don't pay attention to fashion, and that it wouldn't hurt me to go without lunch because I could stand to lose a few pounds. Hahaha...not the way to get on my good side. It was an automatic no after that, and I was badmouthed for a week or so before it died down. I lost a "friend", and gained some self respect.