I wanted to see if they had collected data on how often the wallet was returned with the money. That was not part of the main experiment design[1] where the wallets were not actually collected, but they did collect wallets in Switzerland and Czech Republic to see if it was common to return the wallet, but keep the money. For these 2 countries at least about 99% of people did not keep the money when returning the wallet.
[1]https://science.sciencemag.org/content/sci/suppl/2019/06/19/...