As someone who lives in Japan I believe this is not a result of "Japanese people being more honest", but rather: - Availability. There are police stations (kobans) and officers on the street everywhere, just a few steps away from wherever I may find something. Turning in a lost item has no friction. All it takes is a few extra steps. In the U.S. there is huge friction - I would need to go out of my way to go to a pol…
Many years ago where [1] I was working as a designer of test equipment the head of the drafting department had a saying:
"If you make the right way the easy way people won't do things the wrong way."
He ran his department on those principles and got things done accurately and quickly.
It looks like the Japanese have the same idea.
[1] Philips Mullard semiconductor plant, Southampton, late 70s, early 80s. Such a long time ago I can no longer remember his name.