More than one person I met in Japan told me a story of someone accidentally leaving their wallet on the seat of a train, only for another passenger to chase after them to hand it to them as they left.
During the couple of years when I lived at the end of a metro line in London, I must have found about 5 wallets left on the train. All but one were the type that just holds the transport card and perhaps a credit card, but still.
I've handed people stuff they've dropped many times and usually get a polite thank you for the effort. The idea that they would be hostile to you is just crazy.