Sure, it's my responsibility, and I fulfill that responsibility by returning to retrieve them. I'm not counting on someone else to track me down and deliver the lost item. All I want is for people to mind their own business and refrain from taking whatever property is not being actively guarded.
I don't see why the fact that another person lapsed in shis vigilance makes it morally acceptable for you to take advantage of that lapse. As Shai Gar elaborated, society would be pretty messed up if everyone behaved that way. We function with a basic respect for property because we can't afford to spend our time stealing each other's rather than producing our own and trading it consensually. I could go around picking pockets, blaming the owners for leaving them unbuttoned, but instead I recognize a categorical imperative along with most of the rest of society.
Also, keep in mind that the scarf was in a theater, and if nobody came to retrieve it, it would be up to the theater's owner to decide what to do with it. It does not become fair game for any other person who happens to be in that theater at the time. Front lawns are just as easily accessed, but that does not make it moral to walk onto them and take the gardening implements that are left out. Nor is it moral to toss a Salvation Army bucket into the back of your truck when the bellringer leaves for a bathroom break.
I understand what you're saying, and I do agree in some ways. Momentary lapses in vigilance are something probably everyone experiences from time to time, and society does function a lot more smoothly because of the fact that most people do not take advantage of them, but this in itself does not make it wrong. It would be wrong if the OP's friend intended to take the scarf all along, or if she deliberately went out of her way to make it so that the owner could not retrieve it. In this particular situation she probably
was wrong to take it, since it was in a theater, and all theaters have lost and found boxes, and also, she didn't wait for the person to come back. But if she had, then there would have been no malicious intent on her part, and her taking the scarf thereafter would not (imo) have constituted a morally reprehensible act.
Also, taking something from somebody's front lawn is a completely different situation to the one described by the OP, as is taking the salvation army bucket. In both of these scenarios there is a clear and obvious owner - the homeowner, and the charity - therefore if one were to take these items, it would entail disregarding the fact that there was a specific party to whom they could have been returned. That would be clearly wrong.
But say, for example, instead of a salvation army bucket (which usually has a label on it, which would identify the organization it belonged to), there was just a $20 note on the ground. Would it have been wrong for her friend to take that money, seeing as it was lying around without an owner? In my opinion, no, as long as the person who picked it up made every reasonable effort to determine whether it belonged to someone. I guess in a way it is all subjective though, because what is "reasonable" is going to vary depending on who you ask.
