What you said is different. It also depends on what the lost/found property was and the setting in which you find it. It's impossible to find out who that $10 bill in the street belongs to. The smartphone has information and contacts you can use to find the owner. You can even drop it off at the carriers store and ask them to contact the phones owner.
I don't think my neighbors in my apartment complex would like me banging on random walls to turn things on and off. Like wise I would get pretty mad if i heard someone just banging on the wall throughout the day.