[_delirium]

It's not really a proper solution, but libraries serve as a kind of alternative "official authority" for things like that in the part of the US where I currently live (one of their many unofficial jobs that aren't properly accounted for or funded). People seem to drop off stuff in the library even if they didn't find it there, because it's a place you can easily enter, and librarians are perceived as having some kind of official status (being government employees), but compared to others are seen as approachable and pretty honest and benign. So people assume the librarian will probably know what to do with the wallet and probably won't just pocket the cash. And, many people are less apprehensive about walking up to a library front desk compared to walking into a police station.

[interfixus]

Well then, welcome to my world. Where I live - provincial Denmark - these days our local police resides behind a desk ... at the library. Mind you, this is police of a variety radically different from just about any aspect of American police I've ever seen described. Our police structure and organisation is in shambles, but at the personal level, a police officer is first and foremost a service provider, and the ones I've interacted with over the years have been unfailingly professionel, non-threatening, and polite. Also: Fit and never, ever overweight.